Winter Projects - Resin Advice

[stom]

I've set myself a few projects to complete on 2654 this winter and am looking for a bit of advice on epoxy resin.  The first project is to be a new set of foils and a rudder stock.  The current rudder stock is on borrowed time as its already been bodged back together by one of her previous owners.

I've been looking at different types of epoxy and  was wondering if anyone had any experience with the following(feel free to point me in the direction of more cost effective/suitable resin suppliers f you know of any);

http://www.ecfibreglasssupplies.co.uk/p-2457-mas-flag-epoxy-kit-medium-cure.aspx

Also can anyone give me an idea of the quantity of epoxy required for rudder, centreboard and rudder stock?

I've also got ideas of making a carbon rig for her at some point, although i need to get my laminating skills up to scratch first.

[roland_trim]

I'd strongly reccommend heading down to the sticky weekend (date TBA). It is a great way to learn from the fleet.

Sucking eggs:
For home laminating if possible for over the winter work have a warm(ish) workshop. One idea is to decant the resin you are going to use and store it in the house the night before using it to ensure it is above 15oc (most resins get stodgier when cold and need to be above winter temperatures to set). Most resins also need a bake to achieve full strength.

Resin:
As for resin quantity you are aiming at the same weight of mixed resin as the cloth. Cruise the wiki and there are several foil layups (EJ's build page - http://www.uk-cherub.org/doku.php/tech/3206build has our mast reciepe).

H&I use Sicomen 8200, not the cheapest but we like it. I can happily decant you a kg or two (I think the last order was about £15 a mixed kg inc VAT).

[Will_Lee]

A 50% resin ratio is very good going for a wet layup, and this does not take into account filling/buttering/filleting use.

Also there are huge discounts for quantity - often if you buy the next size up from what you need, you are nearly getting what you need plus nearly as much again free. (Compare the 5kg price with the 1kg price)

This is why people are absolutely fine with giving you quite large quantities of material for your first job or two.

Good luck!

(Also - A stock is an easy starter job. A rudder is ok, but a board is a difficult job. An intensive 'sort out' of your board  may give more bangs for buck than starting again.)

[phil_kirk]

Making the components for a stock is very do-able on a sticky weekend.

To get good results the resin needs to be at room temperature 18-22 dgrees C to provide a good cure.  Some resins are tolerant of lower temperatures but take longer to cure.  This may not reward you with good material properties. 

My approach for winter laminating is to bring the resin indoors overnight,  laminate in the garage warmed by a fan heater and bring the peice indoors afterwards.  Make sure you put the curing object on to polythene and newspaper to stop it sticking to the carpet!  If you have to cure in a shed or garage some wall insulation panels or old blankets can be used to make a tent around the item to be cured.  if this covers a thermostatically controlled fan heater you can achieve a decent temperature for little electrical power.

Within reason a higher temperature will give a faster cure.

[stom]

Thanks for all the replies!  All wise words much appreciated.   We'll certainly try and make the sticky weekend when dates are set, as I have much to learn about the art of composite layups.

BornSlippy it would be great to take you up on the offer of resin although I live in Chesterfield so it may need posting?  Could you email me on tomjslater(at)gmail.com if you think it would be possible to work something out(must get class memebership sorted so I can PM using the forum).

I'll heed advice about not making a dagger board yet. I've repaired all the damage to the original, but when it was originally made only resin was used to build up the trailing edge with no fibre reinforcement.  As a result it's really fragile and already has a couple of new chips out of it.

The rudder has to be replaced.  It's too short to use as a dagger style rudder and also looks to be made from a plywood core which is delaminating.  I guess i'll have to learn the hard way with that one...(It has to be the first project, which I can then use to form the sleeve for the stock)

Can anyone give me the dimensions of their rudder(length, width)?  Also I'm thinking of using a NACA0010 unless anyone has a better suggestion?

Thanks again for all the advice.

Tom

[phil_kirk]

NACA 0010 is a good rudder section.  There are a few slightly faster ones but the diferences are small.  Full length of the foil allowing for the blade in the stock should be around 1m.  most of the foil can be paralell although it is probably wort sweeping the leading edge back in the lower third if you are not fitting a T foil blade.

Cord I would suggest 210mm minimum.  Smaller cords can be used with with T foils fitted but the sailing difficulty factor generally increases with smaller cords.  From this and your section the max thickness of the core wants to be about 19mm. You can by foam this thickness but if considering other laminating projects or hull mods buy 8mm foam and layer up to make thicker cores. 

With a rudder balde you can get away with 80 kg /m^3 foam but it is easier to shape a high density foam core (200kg/m^3). You will want high density for the centreboard so it may be worth buying a sheet of that at the thickness you need for the centreboard.

[Neil C.]

Phil, that's very close to the rudder dimensions on Lost in Space - 2658, a similar era boat to 2654. Lost has very nice professionally made foils from Bloodaxe Boats (non-T-foil). The rudder is a NACA 0010 section 1080mm long by 230mm chord. The daggerboard is 1400mm x 330mm, a bit short and wide by today's trends.   

[phil_kirk]

Slippery when Wet's rudder blade was a pivoting style when we bought the boat.  But a constant cord. The bottom gudeon on the aluminium rudder stock was badely worn so we realised we needed a new stock. 

We turned the blade upside down, removed the old glass sheathing, bonded some mahogany around the old top to make the round head into a square and did a lot of planing and sanding.  The core was cedar I think. We tapered the cord so it ranged from 21cm at the top and middle to 18cm at the bottom. It was a NACA 0010.  Hence my suggestions above.

We built a new dagger style stock around the blade. 

I would reccomend using the router/ contour method of shaping a foam core.  The core will have a smaller cord and be thinner in section than the finished blade allowing for the laminate thickness and allowing you to have a solid trailing edge.
For my recent rudder blade i changed the layers of cloths i had used previously to provide more protection to the leading and trailing edges.   Both get a bit of wear from the stock. 
 I put a strip of weave around both edges (lengthwise) before adding 2 layers of uni.  The first uni layer extended all the way down the second layer extended 2/3rds the way down. The unis went around the leading edge but overlapped the trailing edge on both sides. finally a layer of weave was added. this overlapped the leading edge and extended past the trailing edge.
Once vaced dry the trailing edge can be trimmed down to the intended cord and the foil faired. 

If you have your design, the core material we could get a blade shaped and layed up in a day. 
Good luck

[stom]

I presume this is what you mean by the router contour method?

http://www.youtube.com/embed/9KK-3kfX7x8

I'm going to place the order for materials and resin this weekend, as I've got some time off work in a couple of weeks and I'm keen to complete the first project.  I'll update this thread with progress of he build.

Thanks again for all the advice.

Tom

[phil_kirk]

I can't open the you tube link at work but will check later at home.

You get a good product if the board is vac bagged.  This may be difficult for you to achieve without all the kit but if you had the core and materials ready for the sticky weekend we could lay the rudder up and vac it first thing, make the tiller tube  and then make the sleave on Sunday morning.  So long as you can fit a curing object in the car to take home that would work. 

[phil_kirk]

Yes the you tube clip is what I meant. 

My approach is to route off all the material on the thin side of the line instead of cutting grooves. This reduces the sanding required at the end. 
Using high density foam of the correct thickness avoids the need for carbon stringers or pre laminating sheets of foam together.  It saves a lot of time.

If you want to taper the bottom of the rudder you can mark on curved contours before routing.  This involves working out the thicknesses and offsets for sections of several cords.  You can make the foil tapered though which is simplest.