Building Paterson 8 in Dubai

[doug1720]

Thinking about ordering some sails.  I was wondering about which manufacturers are working with the class and therefore know what works.  I see a lot of boats with Hyde's - is there a contact there that I can talk to?

(I am still in the market for a set of second hand sails as training and backup!)

Doug

[doug1720]

I can provide you with the layups that I used for other parts on the understanding that I can't gaurantee they are correct.  I have put full rig tension on the boat without a squeek from her but not sailed her in anger.  I expect all is ok but the lay ups would be unqualified.

Phil,
I would be very intersted in the lay ups as getting serious on all the tubes now!  email is dgh200 at gmail.com

Doug

[doug1720]

I have another question on the crew deck.  I am going for 29er style all concave.  So all control lines, pole, etc on top.

I am presuming I need to plan the placement of fittings and I am using low density foam (divinycell H80) that will not stand upto any fittings being screwed in?  I am ok to put high density foam where required.....is there any information or pictures that would enable me to locate where I should strengthen the foam?

Unfortunately I do not have the opportunity to see another boat, otherwise this would be a lot easier!

Thanks,

Doug

[Phil Alderson]

Hi Doug,
Have you had a look at Rigging Design on the wiki?

A twin spreader rig is required with a masthead kite, or you will be needing a telegraph pole to keep it in the boat.

Thinking about a stiffer rig, this realy depends on your weight, the point where you start to depower will always be where the rig generates more power than you can hold down. You want to depower once you are flat wiring, it does not matter too much weather that happens every day or just occasionally, it should still be at the same wind strength.

For the fittings hard points, you do not have to use HD foam, you can use fronting plates where you bond a carbon nut plate to the deck where you want the fittings. or you can bond short carbon rods to the deck and tie the fittings to them, I will search out some pictures.

[JimC]

I suppose I am explaining that because of the conditions here I will be in fully powered up mode a lot of the time and therefore eering to the tree trunk   I think in the UK I would be looking at more of a balance between power up and depower.

Maybe but... you are going to be sailing a boat that is far more heel sensitive than anything you have been in before: flat is nearly everything. And I get the impression that winds in hotter parts of the world are likely to be particularly gusty due to heated air rising. There's also the business of learning to sail it. So spring in the rig gives you much more chance to keep the boat on its feet and driving...

The first time I learned about this was when I rerigged Halo from a tin mast to a plastic one. The original rig on Halo, was pretty much the telegraph pole to end all telegraph poles.... I was very much working on the theory that maxpower was needed for fat forward hand, so it had a solid section (too stiff - Superspars announced the M7 about 6 weeks after I'd ordered an M3) and high hounds to enable a high hoist for the kite.

The kite hoist is just above the top batten, and the jib about the second batten...

When I got a C-tech carbon rig the jib hoist stayed in the same place, but the mast was around 410mm longer so around 20% more topmast...


The difference in how much more manageable the boat was was phenomenal...

I've been learning a lot more about this playing with the rig on my Canoe... Whilst I like to think I wasn't a bad Cherub forward hand I'll cheerfully admit I'm a pretty crap helm, so I do need all the help from the boat I can get, and I sail pretty much exclusively inland, and base, at 400 acres, is not a huge pond. My boat has got an ex Shiny Beast 5515 Superspar, which is 25% thinner wall thickness than the usual thickness for ICs, so is basically flexible. Add to that I am now somewhat fatter than I was in Cherub days, so am towards the top of the Canoe weight range.

The boat has no kite, so I have a single spreader rig and thus rather less scope for using rig setup to tune power. I set the boat up originally with loads of gust reponse for learning - such that it was actually quite difficult to get sufficiently powered up to require hiking off the end of the plank.  So loads of aft rake on the spreaders - as the gust hits the increased load on the shroud tends to push the mast forwards, take depth out of the middle of the sail and dump the leech.
After about a year I felt I could deal with less gust response, so ran the spreaders neutral. Grief! What a cow the boat turned into! Instead of accelerating in the gusts she just staggered, heeled and stopped... I must own up to being completely gobsmacked by the change in boat handling... Needless to say this was very slow as well as not much fun, even if I could get the weight out further and had more power, and spreaders settings reverted quite a lump of the way back and the boat was fun tosail again. Since then I've been playing with options - adding more cabon to various bits of the stick - to get more power in without compromising the handling too much, I could go on, but you get the picture...

Now because you need to be running a two spreader rig with caps to support the kite you have a great deal more control of the rig than with a simple rig like the Canoe, and its pretty easy to dial power in and out, chiefly with the caps and checks (D2s). Its probably also easier and safer to add stiffness to a mast by gluing more carbon on than it is to take it away.

If it turns out too floppy you just bang a ton more caps and checks on and get some more luff round put in when it comes to get the sail recut to sit the mast better (I don't believe its likely that you'll get the luff round right first time with a home built mast so always figure that's coming). You can always bang more carbon on later. If its too stiff, on the other hand, the whle business of working the boat up and learning to sail her will be horrible and the boat will be slow. I am quite convinced these days that far more races are lost with too stiff a rig than too flexible a rig, especially in unsteady winds, which according to everything I've read you are going to experience...

[Banshee Ambulance]

Can't really help with the rig im afraid. However, a great guide to fitting bits onto sandwich structures can be found on the Carbonology 18ft Skiff build blog. This is the method I would use as you can think about where fittings will go after you have the boat in one piece. 

[john_hamilton]

do you man the bit about ply and a stanley knife?

[Banshee Ambulance]

Ply and Stanley knife - yes! Seems like a jolly good idea to me. If it works on an 18' it will probably work on a cherub.

[Will_Lee]

Chopping foam out and replacing it with HD foam or ply used be quite common in Cherubs: In about 1997 the N12's starting experimenting with gluing the fittings on. I remember being sceptical, but it is pretty much universal in modern Cherubs.

You bolt the fitting to a circle or oval of carbon plate. You then chop off the bolts flush with the end of the nut, put the whole assembly down on the boat, draw round it, and then rough up the deck before bogging the whole thing down. If you wrap up the fitting in tape or cling film it makes a good handle to hold it down while you clean up the fillet.

All of Atum's and Antidote's fittings went on with fronting plates. These are like backing plates...only on the front! None has failed so far and both boats had their socks sailed off them. In fact the first of Antidote's jib turrets did come off. I cockily glued it straight down (a 50mm by 50mm square) rather than making it a circle. It now has a 100mm circle so Lucy will have to pull pretty bloody hard on it to pull that one off.

It takes one epoxy hit so is quicker and easier than the old method.

For the fancy minded you can taper the edges of the plate to reduce the stress-riser. I do this if it is a high load one.

If the deck is flat such that the bolts are holding the plate away from the deck you can make a couple of holes in the top skin of deck to allow them to recess in there. Be sure to put bog down the holes though as it is the bog which grips the nut to allow you to replace the fitting when it knackers. I have done this a lot - esp the floor block for the kite.

A variation is putting the bolts under the plate sticking up. Andy and Jill Peters did this on their boat.

Variables:

Thickness of the plate - about 10 layers of 200g plain weave or equivalent. You should not be able to bend it by hand.

Size of the plate - about 10mm from the nearest approach of the fitting, unless the fitting is raised like a jub turret or under specific peeling load like the block which sends the kite halyard up the mast. This block was a fronting plate on to Atum's Stump, but on Antidote it is a large fronting plate on the deck.

Shape of the plate - circle is easiest to make using a holesaw. Avoid corners because they aid peeling.

Bog: epoxy+colloidal silica+glass bubbles. Make it up so it is like butter icing. Paint a little neat epoxy on the two surfaces to help a good bond form. Pile the bog on the fitting in a shallow cone so any bubbles get pushed to the edge. When you put it on the boat press down hard. I usually lean a heavy thing on it to keep it still while I clean up the fillet with a tongue depressor or coffee stirrer.

[Will_Lee]

=2688#th_feb_20061]http://www.sailingsource.com/cherub/test/doku.php/boats/2688?s[]=2688#th_feb_20061


Middle pic shows how we did it on Atum.

I did Antidotes while reviding for my (MSc) finals so did not take too many pics.

[JimC]

Chopping foam out and replacing it with HD foam or ply used be quite common in Cherubs: In about 1997 the N12's starting experimenting with gluing the fittings on. I remember being sceptical, but it is pretty much universal in modern Cherubs.

1997? Several fittings, notably the kite halyard hoist/drop turning blocks, were installed like that on Halo in 1989 and I don't remember thinking it was especially  innovative so I imagine I must have got the idea from someone else, presumably Amber Dragon, Johnny F or possibly Norwegian Blue, I don't recall. It was a ply plate glued on with glass all round the tapered edges:  carbon was less prevalent then,  but the same principle. And just to prove it, out of the bits box:-



Goodness knows why I left the bolts so long. The nuts were on the underside so they could be locked in by bog and give me half a chance of being able to replace the fitting if damaged. I never tested the theory!

[doug1720]

For the fittings hard points, you do not have to use HD foam, you can use fronting plates where you bond a carbon nut plate to the deck where you want the fittings. or you can bond short carbon rods to the deck and tie the fittings to them, I will search out some pictures.

Thanks.  Have you got a source where I can buy these from?

Doug

[doug1720]

 So spring in the rig gives you much more chance to keep the boat on its feet and driving...

Thanks for the advice and a key point as I think this could end up being more about swimming than sailng.   So a floppier rig and adjustment through rig tension.  I will think about layup and post what I think I should do.

[doug1720]

Middle pic shows how we did it on Atum.

Thanks for all the information....another thing to make!

[JimC]

Thanks for all the information....another thing to make!

As the project progresses you'll find the sad truth of home boat building - that it takes just as long to make up a fiddly little bracket as it does to lay up the entire outer skin of the boat - and there are a lot more fiddly brackets! Its why the mass production boats take so many compromises on layout to make them affordable to build, but also why our boats can be so much nicer to sail...