UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: Clive Everest on October 03, 2012, 09:51:48 AM
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As anyone who could tolerate listening to me at the Nationals will know I have been planning a new build.
I did not want to start a forum topic until it was actually under way, which it now is:
I am posting as I know that I will get a lot of helpful hints on lessons others have already learnt,
I suspect that a few will be interested in what we are doing, and hopefully I can inspire others to follow or join this project.
I felt after a year sailing Cherubs that the new boats are markedly quicker than our old slug but also a lot harder to sail.
Whilst this was too our advantage at the nationals it was fairly unique conditions and we wanted a new boat for next year that was closer in speed to the latest boats whilst trying to make it as sail-able as possible.
Almost as soon as we were home we started to try and form these ideas into a design.
The biggest change from most recent Cherubs is to move away from tubular wings to solid wings.
Under the current rules solid wings can be wings and do not have to have a continuous sheer line as per the old rules solid wing boats.
It was felt that solid wings could give a number of advantages:
• A lot of capsizes in the new boats seem to occur at low speed whilst maneuvering. By having solid wings there are more options on where to put your weight.
• The tubular wings often hit waves at speed this is not fast. A wave hitting the clean underside of a solid wing will not drag in the same way; it can positively add righting moment.
• Solid wings can therefore be very slightly lower which all helps with staying upright at very low speeds.
• When they hit the water when nearly stationary they will not sink as fast.
The hull will have small flares that run all the way to the bow and transition smoothly into the wing.
Underwater I wanted a hull shape that was not so different from the current designs but perhaps more orientated to slightly lighter winds.
The racing is closer in lighter winds, giving up time in strong wind races for time in light weather races will result in a net gain in regatta position even if it results in a degrading of the PY.
My hull design therefore has slightly more rocker than most of the new designs, but still very slightly less than Ronin. We had a number of flat out runs side by side with Ronin during the year and they did not seem to be suffering loss of top speed due to excess rocker.
The chine entry angle is much the same as the other modern designs.
The max chine beam is on the 450mm limit 85% aft. Perhaps very slightly further forward than the E6 but with no compromise to the entry angle.
Looking at pictures and from direct observations it appears to me that water only releases at the chine a small percentage of the time. Often the chine is either fully immersed or the release has happened before the chine. This is in contrast to a speed boat or a sailboard where the water truly does release at the chine.
On my hull the chines are therefore slightly higher and less defined. The hull has a tight turn of bilge below the chine with a truly flat bottom panel. The higher chine line probably means that the water line entry angle is actually finer on this design, and the mid ship water line beam may be narrower despite the max chine beam being slightly further forward.
The wetted area should be lower.
Any attached drawings are have only been developed to allow me to see how things are going to work or to allow bits to be made.
A key consideration was to try and find a way of building the boat whilst reaming employed and married before Alex leaves home.
This has yet to be tested.
I will post some more over the next few days and as the project progresses.
Clive
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Import of the sections into 3d cad package.
The lofting can not handle the wing transition.
Snout not shown.
How do I directly inset images into the text?
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Hi Clive, thanks for sharing.
What will the boat look like on the top side? Will there be a foredeck?
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No Foredeck. I considered foredeck and under floor spinnaker but decided that they are luxuries that would not fit in the Cherub weight budget.
Wings are going to have a 49er style return to stiffen the outer edge.
There is a grey area on the rules here as it contravenes the letter of the anti multi hull rule. 4.1.6
The rule states that "Note: It is not the intention of this rule to prohibit 'tubular
wings'. These are not tubular wings. If they are deemed illegal so would all boats such as Subtle moulded with a return on their gunwale.
If this is the case I will fill the return with polystyrene, however I do not think that it is the intent of the rule.
The shrouds will be near the wing tip with horizontal compression struts going to a king post, and a mast step that is level with the wing tips. This will support the front edge of the wing.
There will be support tubes supporting the aft corners of the wings.
The forward flares should be small enough with enough compound curvature not to need support.
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Thanks for sharing these Clive.
Im really interested to see this - The solid wings and raised/softened chines are features of a design I have had gestating for some time so its nice to see im not out on my own here. I'm looking forward to seeing the updates as things progress.
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I notice from the sketches that the wings do not extend aft of the transom. Is this true or a simplification of the scetches done to date. You may wish to consider kick bars along the wings where the gunnel of a racked boat would be. These could also be used to stiffen the wing pannels.
We realised the issue of racks catching the water or deflecting spray from the boat by fitting the racks on Enumbers an inch higher than antidotes. That appears to would most of the time.
If you are a perfectionist it can take a long time to build a boat. But I hope that Alex will be keen to help. To speed up the build and reduce the impact on Family consider getting the shells built professionally. You can build other components at the same time and bring the lot together. Good luck!
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Hi Phil,
The images in the first 2 posts do not accurately reflect the wing design. They are a simplification whilst working on the hull form.
the 3rd one is a more accurate representation of the wing detail.
The rebate in the back edge of the wing for a back foot aligns with a kick bar that runs the full length of the wing.
The kick bar can be seen on the transom view.
The wings are going to extend 400mm aft of the transom. A lot less than some wheelie bars, but by having the inboard rebate for the back foot I hope to be able to trapeze with my body angled back with a safer foot position, when sending, but have both feet on the outer edge when feeling more confident.
I have never ever been accused of being a perfectionist when it come to boat building.
I will give a bit more detail about the build process once I have done a bit of real work. It has been rather limited in the last month.
Clive
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Hi Clive,
Your sketches show an even rocker approx 50% before the centreboard and 50% after.
I'm no expert but Loco's rocker appears to be more forward with flatter sections aft. (NB Big Issue) I had a good look a few months ago and came to that conclusion. The aft sections actually look to have relatively little rocker.
I think you are right about wings. We didn't get a chance to show off Loco much this year but the consensus seems to be 'Fast in light, gets left behind in medium (but not by much) and comes back in the heavy stuff'.
The 'Gets left in medium' might be cured by a better T-foil as Loco's is (I am told) of an older design.
Can't find Big Issue line drawings but I suspect Loco has more rocker than Ronin.
I think there is speed in Loco's hull and getting the right bow attitude in medium stuff could unlock it...I'll dream on anyway.
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I agree there is more scope for this type of design to appeal to newer cherubists and crews thinking about getting into Cherubs, (as standing on it should give alot more initial confidence than when launching yourself around a racked design for the first time!).
Good on yer Clive it looks great! I hope to see it soon. when you thinking on first time out...?
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To answer the above, the rocker is still low compared with almost any other class of dinghy at just 65mm.
Half of this is of constant curvature from end to end.
Half has a curvature of zero at the transom increasing linearly to the bow.
I am not looking to compromise speed against other boats. I am trying to find ways of making a full speed modern cherub slightly easier.
I hope to have it afloat for Chew.
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I want the build process to be as simple as possible.
The wings, decks kick bars, transom and internal structures are being built out of flat carbon foam panels by Fibre fusion.
They have a 100 ton press and make very high quality panels.
100 tons on a 8x4 sheet is equivalent to nearly 4 bar pressure. The laminate quality is well above anything that can be achieved without an autoclave.
They will then water jet cut the panels to shape.
The water jet produces a very fine clean cut with sub mm precision.
Pic shows the panel kit.
It is possible to rout out a line across one side of the panel and fold it to make gunwale returns and kick bars.
4 panels are needed.
The hull has been designed as a multi faceted planked design.
There are a total of 11 planks around the girth from the wing intersection each side.
3 planks form the turn of bilge. The change in angle from plank to plank is very small.
I have had a kit for the mould water jet cut from 6mm ply. The kit consists of 11 bulkheads and the required planks and various spacers and templates to set angles.
Pic below shows the parts drying out. If my sums are right the planks should fit to the bulkheads to form the design shape.
I will find out this weekend.
I will cover the mould with a layer of glass and self adhesive PTFE release film.
I intend to make the hull out of prepreg carbon foam sandwich.
My experience of the prepregs is that they are easier to get a high quality laminate.
You can place laminate with a lot more precision.
The resins used appear to set much harder. This will be of value on a boat that often ends up on the beach.
The laminating process requires a lot less skill and is much quicker.
The downside is that they are a bit more expensive. They need to be cooked under vacuum and any excess needs to be kept in a fridge or discarded.
The modern prepregs can be cured at 80c and will last at winter garage temperatures for several months out of the freezer.
The foam planks for the hull shell have been water jet cut today.
The first laminate and the foam will go on together.
These will be partially cured.
The corners where the planks meet will then be rounded with a long board and the second laminate applied. The whole lot will then be baked and fully cured.
The laminates join on a flange that is the same angle as the wings. The wings and deck will join onto this flange.
The internal structure will be fitted followed by the deck and wings.
I will get a pro to finish and paint it.
I will post as it progresses.
Clive
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Nice looking boat. Be interesting how she goes. I shall be very interested to hear how the multipanel approach works out. There are lots of potential advantages, but I've wondered if you'd lose a lot by not having all the fibres going across all the joins. Or do I misunderstand you and the shell will not have pre laminated panels?
Wings are going to have a 49er style return to stiffen the outer edge.
There is a grey area on the rules here as it contravenes the letter of the anti multi hull rule.
I can confirm it was never our intention to prohibit that sort of thing when we were writing those rules. Halo had a similar return on her (wood) gunwhales back in 1989: it was mainly intended to provide a bit more area for trapezing feet and longitudinal strength for the shroud loads on a predominantly glass boat, but it was also very handy for picking her up and for climbing onto an inverted boat!
I'd also planned vaguely similar solid wings for a width extension for Halo, and got as far as getting some panels made, although in the end (IIRC) they ended up as part of Atum Bom's interior framing. Your thinking on drag of solid wings is similar to mine - and I was also thinking about aero drag - but of course there's another school of thought that suggests you save more drag from the spray that never touches the boat than you lose from the spray that hits the beams harder. I have no idea how you'd test that.
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Hi Jim,
Long time since we last met.
The wings deck and internal structure will be from pre laminated panels.
The hull shell will be laminated as a single continuous moulding but the un laminated foam for the panels for the shell have been cut to the required panel shape.
The main advantage of the panelled hull is that the mould construction will hopefully be much faster.
The hull shell is a relatively small part of the structure. The shell build area is just 4.4m2 The shell uses requires 1.5 foam sheets.
The deck wings and internal structure require 3.5 sheets. Most of the build is effectively being done by fibre fusion in their 100 ton press.
The only laminating that I expect to do is the taping of the deck and wing joints.
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Gotcha, I understand now:-)
Press - when Halo was built Alistair and Matthew Cope showed me how to make flat panels with a press consisting of two sheets of chipboard and every sailing magazine in their house to weigh it down evenly. Somehow I doubt we made 4 bar pressure [grin].
Yeah, its about time we ran into each other again.
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To answer the above, the rocker is still low compared with almost any other class of dinghy at just 65mm.
Absolutely...and I'm really pleased you decided to design...and I think I was cheeky to offer you advice :)
When I looked again I could see that the rocker was graded.
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The only laminating that I expect to do is the taping of the deck and wing joints.
This sounds like something I asked about earlier in the year and got a negative on...this boat could be built from a kit of pre-laminated parts, yes?
...but currently because some of the parts are an expensive type of carbon sheet it wouldn't save money?
I was hoping pre-laminated carbon sheets were the new plywood.
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Clive,
It sounds like you have really thought the build through. I'm in favour of a boat which can be built as a kit of parts. We laminated the flat panels for our bulkheads from one sheet of foam. I built a flat bed of timber joists and plaster board to laminate the flat pannels on. I vac bagged the panels and weighted the bag down onto the flat bed.
The kit boat concept allows, as you have suggested, a quicker build and less initial laminating competance. Just having accurate templates of all the flat components for the E5 build would have saved a lot of time.
With there being a lack of second hand 05 rules boats this concept could allow the class to grow more rapidly.
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Clive - it occurred to me that the big advantage of racks is that you have two trapezing positions - either from the hull or the rack. This makes getting in and out easier. I might go as far as fitting a (rear) foot stop to Loco to help the helm come in smoothly...currently there's nothing to stop you until the leeward gunwale...
Wings might mean you just adopt 49er tactics and walk around but just something to think about.
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The mould is all assembled.
It took about 8 hours to assemble. I suspect that a perfectionist would have taken longer.
If I was doing it again I would have had even more bulkheads. I had them every 370mm and the 6mm ply planks were not 100% stable between them. I could have used thicker planks but they might have become harder to twist.
Thicker bulkheads would have been easier to hit with a tack when tacking it all together.
The ply planks fitted to the form accurately however they needed to be positioned carefully.
Next time I will put castelations on some of the bulkheads and notches on the planks so that they lock together with everything positioned exactly.
If you look at the Transom view above, Nigel, I am planning some pretty big kick bars.
Clive
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The mould is now with Pete Jary at Zest racing.
He is going to do a bit of fairing on it and glass sheath it to make sure that it is going to be vac tight.
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I hope to mould a shell next weekend.
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Looking good Clive.
Is the fairing so the facetets in the original jigsaw will dissapear in the wood/plug or is the idea they will they be erased when sanding the foam core?
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I intend to keep the facets in the mould. The foam has been cut to the same pattern so there will be no compound curvature in any piece of foam.
This should make it much easier to put the foam down.
I will then loose the corners by sanding the foam.
A small amount of fairing is needed where the ply planks were not quite stiff enough, and the bulkheads too far apart so that the edges of adjacent planks have not exactly aligned.
It was quite impressive watching the water jet cut the foam.
It was able to cut at 1-2m/sec each plank was produced in just a few seconds.
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You are going some, Clive!
W
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At my age anything else could be very risky.
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This looks amazing,
My only complaint is your use of solid wings.
As I already have a long list of work to do on EJ and adjusting wings was one of them now it looks like they will be solid aswell.
It is something I always thought made sence though I couldn´t put the argument aswell as you.
The best thing is seeing new ideas in the class.
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I have just had a very productive long weekend working on the boat with some great assistance from Roger Angell.
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After the first cure we long boarded the foam to make sure that it was fair and that the turn of bilge was a smooth curve.
this was about 2 hours work.
Getting the hull off the mould was very difficult.
I suspect that the mould should have had a bake before being used. I think that it all changed shape very slightly during the first pre preg cure and that this locked the hull on.
It probably did not help that we got impatient and wound the bake up to 100C.
At one stage I thought that we were going to have to take the mould apart to get it off.
You can see dents on the back of the boat where we were driving wedges in to try and get it off and this was after releasing the top sides all the way round, and using PTFE release film.
The hull shell weighed 6.98kG off the mould.
The FibreFusion internal parts all fit nicely straight off.
The wings and deck appear to fit as well.
There is not much more I can do until I get a centreboard off composite craft to make a case around.
So it is now unlikely to progress significantly until after the inlands.
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Cracking on at pace. Not a bad weekends work!
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Very nice indeed. Looking forward to seeing this come together... (not that we will have to wait long at this rate!)
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That is a very light hull shell!
Who's boat is going to be ready for the dinhgy show then?
I would be very grately if one of the new boats could be displayed on the stand.
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It would be excellent to show on the Cherub stand what can be done very quickly and easily with a simple kit of parts.
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May be we could try and build a boat during the weekend.
I suspect that you will want to show a boat built by a perfectionist.
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Some concern has been raised both directly and indirectly as to whether my planked foam construction constitutes a multi chined boat that is potentially in breach of rule 4.1.5.
"Chines shall be fair and continuous curves. There will be at least one chine at least 2000mm long. All chines at some point shall be at least 450mm from the centreline. No part of the outer skin above a chine shall be inside a vertical line passing through the chine."
This is from what I have given GB and MK to try and allay these concerns. I hope that it reasures others.
Hi Graham,
I am pretty sure that there is no problem.
The mould is planked and the foam planks were glued on with the first (inner) skin.
Once this was cured I faired it with a long board.
This started with drawing transverse lines across the planks and then sanding in a diagonal movement across the planks until the turn of bilge was a fair curve, and the felt tip lines had vanished.
The hull is made of 11 planks in total so the change in angle on each plank is very small and only a small amount of foam needs to be taken off.
The whole process only took me a couple of hours.
This section below shows the turn of bilge at the centerboard case. Here the amount of material that needs to be removed during the fairing process is just 1.6mm.
The red is the faired shape.
At the bow and the stern the total amount of material that needs to be removed is less, as the change in angle is less at the stern and the bow the planks taper to just a few millimeters in width.
<image003.png>
It was not my intention to push the rule, but simply to find a construction method that was quick and easy as my time and skill levels are limited.
The boat is currently with Roger Angell I can get him to take some pictures if you like. I suspect that the above will better show the situation.
This picture of the boat under vac for the second skin is the clearest that I have here.
Don’t be confused by the crease in the vac bag or the reflection of the fluorescent light that follow the line of the turn of bilge. It is pretty smooth.
<image005.jpg>
Most female molded boats will be made with planked foam just to get the foam to fit. Mine is however multi chined, on the inside only.
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Short Stealth Merlin?
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Is this the moth/cherub equivalent of the Harlem Globe Trotters?
The Skippy and Ghoul teams combine for one more project.
Personally I do not think the word perfectionist is one of those key words you think of when thinking of the Cherub class.
I work on the basis that if I try enough times one will be perfect by chance.
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I now have a centerboard from Composite Craft.
Thanks for PJ for organising the build in parallel to his.
I hope that there is plenty of water at Babbercombe.
As soon as we are back from half term holiday I can build a case and the hull build can get going again.
Clive
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your crew is going to need a centerboard crane to pull that up!!!
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You can always make 'em shorter, but longer is hard work...
Clive, how long is that one? There used to be a 5'9" limit in the rules, but we dropped it because no-one had made one that long for many years.
Back in the 60s max length boards were common in the UK, and pivoting centrebpards, not daggerboards. Slot gasket hell!
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1660mm or 5'5"
I may well be cutting it down a bit.
I will also be starting a petition for dredging of Chichester harbour.
I have put the board slightly further forward than most modern Cherubs (~100mm forward compared to the E6, This is the same as Ronin and 170mm forward of the Deamon design.)
Moving the board forward helps in light winds as the centre of yaw is moved forward and the immersed bow sweeps less water when trying to steer to small shifts and waves.
It also helps reduce the lee helm when the kite is up.
Moving it back helps in strong winds as the bow is up, so sweeping is not an issue and the natural center of yaw is further aft.
The forward position allows a slightly smaller centerboard and a slightly bigger rudder to give the same foil loading, so that the leeway angle and drag are the same.
We are also going to be using a gnav so sailing with it raised should not be an issue.
Clive
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What cord's are we using for centreboards these days.
We went a bit conservative with E-numbers to keep the CLR nearer the hull with a cord of 300mm. I'm now thinking that a smaller cord and more high aspect and perhaps slightly lower area foil would be faster and just wondering how small a cord we can get away with.
Our board is 1500mm long with 300 mm in the hull. Not extreme by the current designs.
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I shared the centerboard and rudder build with PJ. The centerboard was built by composite craft.
It has a 240mm cord and 1660 span.
This is the same plan form as Ronin but with a different section.
PJ wanted to use a 225mm cord from a 14 mould, and correspondingly longer span.
I would have happily gone to a lower aspect ratio as I think that we are into very small returns and we sail in a shallow harbour.
We both compromised to get them built as a pair.
My boat has 240mm in the hull. I may well cut the board down slightly.
Clive
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Thanks Clive,
I was thinking in the region of 250mm cord so wasn't far off your final solution.
I may have something to do on the sticky weekend then.
A previous post by Dave Roe in a different thread provided a rule of thumb ratio of board area to sail area. Most people's boards appeared to be larger than this. And 'The Pasta Frenzy' is quick in a blow.
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I have just had a couple of productive days with Rog Angell working on the boat.
We managed to mould a cb case and fit it and get the decks on.
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For the 1st half we were able to insert the camera through the holes in the spine and inspect the gunwale join from the inside.
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I also managed to mould a carbon spinnaker hoop on some 32mm silicon tubing.
I filled the tubing with Hayling's finest sand, covered with carbon sock and epoxy and then formed to shape and consolidated with electrical heat shrink tubing.
I should have used slow hardener as the resin was setting quicker than the heat shrink was collapsing so it is not perfect, however I don't have slow hardener.
The silicone does not stick to the epoxy however it would not come out until I had worked some fairy liquid in.
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Very nice !
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Off to B&Q to buy a large search light and a stencil.
Hayling to now be referred to soley as "Gotham SC".
Looking good Clive. Can't wait to see her on the water, and by the looks of it that won't be long. Is Mr A helping with the rig as well? Either way i get excited just looking at the shots.
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Roger Angell is going to do most of the remaining work including spar making.
He virtually sent me home on Friday, concerned that my impatient attempts to get it finished for the Bloody Mary might spoil it.
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Rushing to meet an almost impossible deadline can give you a boat which over it's life will take you more time to re-build than if you had done it properly the first time.
In my book the Bloody Mary is not a race to do when you are getting used to a new boat. There is a lot of traffic and you need to be looking everywhere other than at the boat.
I may bring the ent this year. I know it's cheating.
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Are you sure thats why he threw you out Clive? not because you ate all his cheese and drank all his red wine ?
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Rog Angell has been progressing the build.
Here are the boom bowsprit and trolley.
The bowsprit mandrel is plugged into a motor drive on the wall.
This can be used with a foot switch to step the mandrel round whilst laminating.
It has a lot of torque and is used to wind on 2 inch wide peel ply to bind the laminate.
The winch on the floor is for pulling the mandrel out. 20kN available.
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20kN = approx 1 elephant :)
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When I have been making tubes, I have often thought that a motor to turn the mandrel would be very useful.
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+1
I currently turn by hand whilst keeping tension on with the other hand. On a pole I end up with cramp in my fingers from gripping the peal ply and shrink tape and pole for so long.
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wings, front flares and compression struts are going on:
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The patches on the wings and deck are where carbon plate has been set into the foam to take fittings.
Clive
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Any chance we could see a photo of the underneath of the wing? I'm curious to see what structure is there.
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2 very different boats being built, this is an exciting time.
Seems a shame to put fittings on such a nice lounging platform as they will be pretty uncomfortable to lie on!
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I want to keep the underneath of the wing as clean as possible so that any waves that hit it provide lift and not drag.
There is a 40mm 90 degree return on the edge of the wing.
This is formed by routing the bottom skin and foam, filling with bog and folding.
You can see this in the photo.
With a bit of extra laminate this should make the outer edge strong.
There will be an 8mm pultruded carbon tube set into the edge of the foam around the entire periphery of the boat.
The front corner of the wing is supported by the shroud and compression bar.
There is a strut at the transom supporting the back corner.
There will be a big kick bar running the full length of the wing which will add further rigidity, and separate the rear strut and the wing surface.
The front flare will have additional support from the jib track and the spinnaker hoop.
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latest build pic
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Looking awesome Clive, can't wait to see this on the water
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latest build pic
Blimey, has Rog had a face transplant?
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I think that the Cornish beer might be changing him.
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The Bowsprit has very reluctantly come off the mandrel.
The kick bars and the rear wing supports are glued in and will be laminated in tomorrow.
Tim's "nice lounging platform" has now gone so we might as well fit it out.
Perhaps a mod for the future, no kick / trip bars.
I did not allow quite enough for the gaps between the panels, when I had them water cut, so the gunwale on the edges of the wings have had to be bent down slightly further than I intended to fit max beam.
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That is starting to look like one mean rocket.
The Bowsprit has very reluctantly come off the mandrel.
Our one in December used the shelving and a spanish windlass - 5mm dyneema with visible stiffening of the threads when finished showing it was working fiarly hard. Nicks video of removal the time before. For some reason that shape is prone to sticking.
Think it is time to set up a bit of Wiki to record just how many different people have popped one off Paul's wooden scaffold pole.
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Keep it clean please BS,
we don't want to know how many people have "popped one off Paul's wooden scaffold pole"
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Did you go to a public school Ben?
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...and I thought me and Hayley were the double entendre brigade
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Amateurs ...
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No subtlety
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View from behind.
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This is looking chuffing awesome Clive.
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Clive what a fantastic design! Are you going to make the gunwhale forward of the shrouds thicker than they currently are? They look fantastic that thin but do also look mighty knife like! Thus quite painful if you go for a swing! Great looking boat thought, very jealous!
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Hi Daryl,
There will be a length of 8mm pultruded carbon rod set into the edge of the foam around the entire periphery of the boat.
I have made an adaptor for the dremel to accurately cut a semi circular grove, the rod will be let in and then taped over.
You can see this on the wing return at the bottom of the last picture.
This should make the edge much more robust and will give it some radius.
In a year of sailing Subtle Knife I do not think that we ever hit the forward gunwale.
There may be an issue with grip when Alex trapezes off it in light winds.
If so we will have to deal with it.
I was looking at the tread of some ultra skinny road bike tyres, just got to find out how to glue them on so that they do not come off.
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Nice idea about using the pultruded tube. I suppose with the narrower boats and T foils sticking the beak in isn't as bad as it once was. When I owned LFC Ben Brown managed to break the gunwale forward of the shrouds after going for a swing, after I'd stuffed it into a wave. He ended up with quite a monumentaly sized bruise!
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The mast tubes are now formed.
Unfortunately once they are joined they will no longer fit in the shed.
Final cure and further work on them is going to be weather dependent.
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Looking fab. every time i look at it my thought go to whats it going to be like. Can I book a place for a ride or is Alex not allowing anyone else on it? Any thoughts on it being a 2 piece mast or is it just not worth considering?
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I really enjoy seeing new innovation in the class. I've been looking at the hull photos again - it could just be the foreshortening effect of the camera, but it looks like you've got a lot more rocker there Clive than has been the fashion for the last few years. It also looks super-narrow. With the chines above the waterline the actual waterline beam could be very narrow indeed - is that right? It might need a highly talented Moth-style sailor to manage it. Wait a minute....
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Hi Ade,
you are welcome to a go, It would probably be better to try it with Joe not me.
I had not considered a 2 piece mast. It is certainly feasible but as we leave the diamonds on I doubt that there would be much benefit, except when trying to fit it in the shed for finishing in the middle of a global warming aberration.
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Hi Neil,
It is a very long time since I sailed a Moth, I am sure that Alex's uni cycling skills will be more useful than my distant past.
I am hoping that the design is going to be easier to sail than some of the other new boats. I think that the solid wings will give more options on where to put our weight, and because we do not have as much worry about them hitting the water they are slightly lower.
This should make it easier to get up the high side, the COG is lower, it will heel further before it topples. When a wing hits the water at low speed it will not sink as fast, getting in after a capsize should be slightly easier.
The boat does have very slightly more rocker, 67mm total. I believe that this is the same as Ronin, and sailing against them we never saw that they had any issues with early planing or top end performance.
It is my intention to make a design that is light weather orientated. 1 minute in a light weather race is usually worth a more places than 1 minute in a race when its blowing 20kts.
The design with the lowest PY will not necessarily be the regatta winner.
I have always had a weakness in light winds and Alex's is already showing a reluctance to get out of bed if he cannot hear the wind rattling the windows.
It felt wrong last year sailing Subtle Knife that a RS200 would beat us upwind in the light but in 5kts more wind and we would lap it.
The bow entry angle is the same as an E5, and probably an E6/7 however the max chine beam is slight further forward.
Whilst the chines are slightly higher, and the sections rounder. I hope that it is not going to be any less stable than the other current designs.
It would be possible to build a much trickier but faster boat within our rules.
I also hope that the rounder sections will be more tolerant of inaccurate trim. We certainly saw this in I14s, and it made boats that you knew were slower very difficult to beat.
A boat with more rocker will be more stable in pitch and that this will allow us to run with slightly more T foil lift and offset the drag that the extra rocker has at higher speeds whilst hopefully reaping the benefits at lower speeds.
Whilst the rocker is higher by Cherub standards it is still very low compared with any other boat that I have been involved with.
Clive
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Thanks for the reply Clive. You obviously have a very well thought out design philosophy. The rounder bottom sections and a bit more rocker idea is something that seems to have paid off in 12 Ft Skiffs as well. The Interdominions have just been won again by a Woof design hull which has a fairly round bottom and more rocker than a typical UK Cherub. Others have designed flatter, chined boats but the Woof has maintained it's dominance for many years now.
I like the solid wings design. I think your ship looks fab all round, and I'm looking forward to seeing it in action.
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Should I be going to Dick Batt for sails?
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out of interest, do we know when and who he made his last cherub sails for? What were they like? My Batt is very old, very knackered but still ACE speedy!
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Hi ade, Dick made me a set just before Christmas. I have yet to try then as I have had to increase luff length to get some extra area in resulting in a gooseneck move. I'll let you know how they perform after I manage to take them out for the first time.
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If anyone is interested I have a suit of 05 Cherub sails made by Batts for sale. Brand new never used. If you're interested I can measure up!
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Re-last photo... "To the batmobile, Alex. Gotham needs us, forget the seat belts. We will trapeze all the way!"
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'ello peeps.
The Batts Stu speak of belong to me, and they are for sale. They are unused and are currently in Mr Tinner's garage in London (correct me if I'm wrong).
If you order from Dick you will get a quality suit of sails and you may just get them in time for the 2020 Nationals.
The boat looks mint clive!
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Looking at Clive's last photo am I the only one wondering where the buoyancy is?
Can't wait to see this boat in action! Looks absolutely awesome and very Gotham City
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Clive, whats the colour scheme on this 'stealth batmobile type vehicle'? or is it still under the official secrets act and only on a need to know basis. I dont think it needs go-faster stripes though!
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It is going to be white with grey progrip.
Not very exciting, but it makes it look like less of a one off, and the Durepox white paint is rock hard.
I hid the buoyancy under the floor.
Clive
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I hid the buoyancy under the floor.
Clive
Yes, very unobtrusively :)
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The noose, just in case it all goes wrong...
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Ah there it is!
Coming together nicely. I can't wait to see the finished boat. only 4.5 weeks to go.
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Whilst the rest of you were getting sticky in Bristol I had a productive couple of days with Roger and Dan.
We weigh the bare hull at 28.5kg. This has given us the confidence we can stay in weight with a few luxuries such as gunwale to gunwale progrip, and add a bit more carbon around the gunwales.
We got the mast up and took some luff curve measurements.
Good progress but still a lot to do.
Clive
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She is looking beautiful Clive, can't wait to see her and you on the water. It's amazing to have so many new builds in progress each with different ideas.
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Very good Clive.
Your heading towards a 40Kg boat in measurement trim. Your should be considering cushions and a beer fridge!
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Now that is a great looking Cherub.
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Just one thought about the jib track Clive. General opinion on the forum in the past has been that 3 points of support is not enough. If the crew flies into the track or into the jib during capsize etc will it break?
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Atum's has 3 points of contact and is pretty bom proof...excuse the pun.
We actually did a couple of races at the nationals with only two points of contact after a bolt came undone. :S
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I suspect (hope) that it depends on what track you are using.
We are using an RS800 track, this has a deep section. From memory > 30mm.
It only has a 3 point contact on the RS800.
Do you have a link to previous discussions?
I think that RV has a 3 point contact as well.
Our boat has a very wide track. Bring on those 2 sail reaches in HISC pursuit races.
I will tell Alex not to fall on the jib.
It is currently attached with Hot melt. We will beef this up.
Clive
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Clive I like this a lot. The only thing I haven't been sure about is the foredeck flairs but seeing the self tacker track fitted (hot glued?) even they are started to make sense.
Cant wait to see it in action!
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Boat is looking very interesting. Is the rig setup with the main shrouds avoiding contact with the lower spreaders?
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Hi Phil,
Yes, SK was set up that way. I feel that there always seems to be a complication with twin wire boats that if you are using the tension in the windward shroud to stop the centre of the mast coming to windward the tension decreases when you get on the wire, and the leeward spreader starts to push the mast the wrong way.
This can be mitigated by running huge rig tension which may be needed for jib luff control, but is not generally attractive.
Maybe we should be running spreaders that pull the shroud towards the mast.
The full width shroud base means that the rig is more like the rig on a cat where the shrouds hold the mast up without inducing huge compression and the diamonds hold it straight.
The spreader angles are relatively flat compared to some.
The mast has a carbon track and so is stiffer fore and aft.
I hope that the flat spreaders will mean that the topmast bends back during gusts and does not drop to leeward.
SK had lowers and inters The inters never seemed to do much but we used to run with a lot of lower tension so that the lower mast was inverted until you applied a lot of kicker. On the new boat we are just running high lowers to just above the gnav. Hopefully these will give enough support to the mid mast.
The mast was built on a 38mm mandrel with 430GPa carbon.
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Do you have a link to previous discussions?
This thread: http://www.uk-cherub.org/forum/index.php/topic,1273.0.html (http://www.uk-cherub.org/forum/index.php/topic,1273.0.html)
2 views - one supports your view based on RS and 'chunkiness' of track does matter.
"It may be worth bolting the track on. 1 at either end and 2 between them either side of the centre. The chunky I track on the e5's doesn't need much support because it is a large section. If self tapping into carbon, fibre glass or epoxy i would always drill a pilot hole first so that only the thread of the screw has to cut through the material." Phil Kirk
"A track supported at the middle and ends does work as the normal high load is when the cark is at the end, the problem is if the car is in the middle and the sheet loads up e.g. in a capsize with crew landing in jib, then it will break. Your cats cradle idea may help with that, longer term I would put a foam-carbon strip from deck to track to give more support." Phil Alderson
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Clive, This is looking awesome..!!!!
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We used a 49er track (which I believe is the same as a RS800 track) on both Atum and Antidote. They were both secured in three places only. It can be stood on without incident.
We had seen the 29er style ones fail in the past, so went for a big and pretty heavy one.
Atum: Short (25mm) lengths of tiller epoxied and carboned to the gunwhales which were a tight fit for the track to go through did the ends. The middle was a carbon plate carboned to the stump to which the centre of the track was bolted.
Antidote: Big flat carbon plates sticking up from the gunwhale and the track trimmed to be a snug fit between them. Bolts went inwards down the centre of the track and nuts was placed in the outboard most holes which allowed it to be attached. Centre was done with a plat attached to the bridgedeck part I think.
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Ours is similar to Antidotes with the exception that a track shaped hole was cut in the carbon end plates and the track sits in those. No bolts or otherwise keeping it in there but in 4 years use it has never popped out (there are 2 bolts through a carbon plate in the middle of the track.
Some bucking of current trends in your boat so will be very interesting to see how this plays out for example I wonder how much windage your boat has Clive when hit by waves and gusts. My experience in a 4 tonner years ago when I switched from a male crew (small wings) to Jill (big traps) was that we had to be much sharper around the boat as the wider wings picked up the wind/ got slapped by waves and in extreme cases did capsize us. However the 49ers seem to cope and those guys are surely no better than us........right?
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Dan and Roger continue to make good progress on the detail.
High build going on the hull next week.
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Starting to look like they are having fun with it. Keep cracking on gents...
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here are a few more photo's i have taken of the build process..https://picasaweb.google.com/101105409795350630457/Everest1CherubBuild (https://picasaweb.google.com/101105409795350630457/Everest1CherubBuild)
enjoy. Dan.
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Hi Dan, sorry can't get that link to work?
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it may work now.. forgot to make the album public..
cheers. d.
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Thank Dan - Can't wait to see this in the flesh.
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Niiiiiiiiice!
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This website needs a Pinterest BUTTON!!! Or a hot line to the people that used to pint those Lamborghini Countach Posters!
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Will we be finishing it on Friday night?
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Probably Phil yes we will! I'd happily display it like that so I'm not stressing anymore ...
He who dares Rodders.
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I'd happily display it like that so I'm not stressing anymore ...
+1
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OMG - I cant see any point for any other dinghy to turn up! Both look amazin!
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I am still stressing.
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Do you fancy meeting up at QMSC for a quick splash on Friday PM? I'll happily man a rib and carry her in and out of the water (in my underpants if it'll make you do it).
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Looks great, think they would have been happier with the look of this layout in Santander!
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Friday? Are you sure?
Just make sure you don't lift a brolly over your head, don't walk under any ladders, don't mention any Scottish plays by Shakespeare, don't shoot any seagulls and if you happen to meet any ginger haired people on the way there make sure you stop and speak to them. And definitely make sure you're wearing your lucky underpants.
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Sorry to grass, but QM Have quite a strict code on wearing wetsuits. I suppose you could do a superman impression!
Alternatively, if asked why you were only wearing underpants, you could say you were only looking for torchies old trailer...
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The boat is looking great, when we brought Primal Scream down to the show we were running so late that the boat had Primer on, and the only fitting was a mast step.
The boat met the mast and sails at the show and we made up the shrouds in the main hall.
http://www.uk-cherub.org/lib/exe/fetch.php/boats/2686-20050306.jpg?t=1343491220&w=333&h=445 (http://www.uk-cherub.org/lib/exe/fetch.php/boats/2686-20050306.jpg?t=1343491220&w=333&h=445)
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On Saturday we managed to launch A + E.
The sail was brief as we were catching a ferry later in the day and are now in France. There is lots of snow here but it feels warmer than Hayling.
Since the dinghy exhib we have had a few issues to fix. The board would not go down the case and it was clear that the mast post needed to be stiffer.
Nothing broke during the sail which is always a relief with a new boat though we did not push it hard.
The boat felt very smooth through the water, and the solid wings were a pleasure to use.
As expected we came ashore with a list of minor issues to fix. The most significant is to change the finish on the spinnaker hoop so that the kite will slide round it.
At the moment it is finished in sprayed mat durepox, and the kite will not slide round it.
We also put the hoop as far forward as we could but this makes the angle that it wraps round greater.
Hope fully we will be in a position to actually race soon.
Clive
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Good to hear that the boat got wet, best of luck getting all the systems working.