Hull Design

Thanks for the information. I’m about halfway with the planking. I’m planning ahead. I was reading on the use of graphite powder and it helps with friction. Do you recommend the use it so it is easier to be pull off lare from the mold? Also, I was thinking of making the boat black anyway, so can I use the graphite for glasing the final hull instead of painting it or is that a bad idea?

The graphite makes the surface more resistant to wear, plus the jet black makes it really easy to see any inperfections. you can use the graphite as a coloring agent.

Bill H

Try Model Sailing Yachts by R Priest and J Lewis, which is a collectors item and you will have to search for it, (try eBay) or A Manual of Yacht Designs by John Lewis which may still be available from Graham Bantock at Sails etc

Bill

HI Bill,
this is the place I have found and already mentioned some time ago in this forum.
http://www.antiqbook.com/books/search.phtml or in UK : http://www.antiqbook.co.uk/

Ref.
PRIEST, B.H., LEWIS, J.A. Model Racing Yachts Their Architecture, Design, Construction, and Handling
Hertfordshire, England, Model & Allied Publications Ltd… Cloth with dust jacket, 4to - over 9¾" - 12" tall. 111pp. No date given.assumed 1966. This book is bound in light ble boards with gilt print on the spine. The edges and corners are slightly bumped as well as the spine ends. The previous owner’s nameplate is on the front paste down. The pages are clean and tight, including the 9 fold-out plans included. The jacket has rubbing to all edges and even a few very small chips tot he corners and spine ends. It is protected in a new mylar cover. An excellent book for the boat lover!. Very Good/Very Good -.
USD 202.50 [Appr.: EURO 160.5 | CHF 255]
– All the King’s Books. N°. du livre: 30580

Cheers
Claudio

I have put a couple of layers of epoxy. I still have to sand it down.

I haved glassed the male plug. I used one layer of S-2 FG 5.6 oz and then one layer of E-Glass 3.6 oz. I’m wondering if I need to add another layer of 3.6 oz or should I just reenforce from the inside.
Does any one have any suggestion?
I used west system epoxy with the slow harderner. This seam to work well I removed all excess resin. it came out great and it pulled easily from the mold.

My opinion? - That’s over 9 oz. of glass fabric plus your epoxy resin weight. Add a few more ounces if you will add paint. Also more if you add a solid deck. I’d say you are fine - if not overbuilt perhaps. I use 2 layers of regular 4 oz. cloth and once a deck is on it is amazingly strong.

Other may/will disagree, but weight is weight and better to have as much as possible in the keel bulb than above the water. Opinion only, I could be wrong. :rolleyes:

if it were m doing the boat id have used gelcoat or top coat for the final coat and coloured it using a pigment to get a nice colour on there.no need to paint then.just my opinion though.

I agree with Dick.

You might want to take a look at this site, which has some useful information on the layups being sued by various IOM builders…

http://duck.sbmyc.com/hull_construction.html

designer,

You are going to pull a female mold of the male plug correct? if so, if you do more reinforcement to the plug, i would do it on the inside.

can you please clarify if you are talking about a plug, mold, or hull? I don’t want to give incorrect information.

Oops, my bad.

Dan is quite right - we should have asked that question.

Thank you for all responses.

To clarify, I’m glassing on top of a planked hull ( so I’m using a male mold) It first I was a little worried becuse it seamed a very sterdy. by this morning, the epoxy has cured more and it seam much stronger. I read up on West’s slow harderner and it mentions that it may take from 1 to 4 days to fully cured depending on the temperature. I’m working in my utility room which the tempeture there is about 65 degrees. I’m not going to be adding any more fiberglass. I did add another thin layer of epoxy so I can sand down. Hopefully that will aslo cover any pin wholes on the hull.

What I’ll do next is to use some of the S-Glass that I have left over to reenforce the fin/keel area. So far I’m very happy with the results. I’ll post picture onces I add the fin trunk.

Also I build the fin by using 1/32 plywood sandwhich with carbon and then 1/16 plywood. Then I covered it with cookie paper (parchment paper) and then used to pieces of wood and I clamp them firmly together. Once it dried I applied an smaller strip of carbon take through and used the same process with the clamps. As a result I got a very sterdy fin. All I have do do now is sand it down to its final shape.

I was surpriced on how well the parchment paper worked, the epoxy comes right off the paper and then you can keep reusing it. Once thing that I found out too late was that http://www.woodcraft.com/ sells an affortable manual vacum baggin system which I would have used instead if I would have known. Needless to say the fin came our very well, much better than one I built last year for a US1M.

So - as Dan asked to clarify - is this going to be the actual boat - or are you going to make a “female mold” to make other hulls from it?

Sounds like this will be the acutal hull to hit the water ???

Sorry, I need to be more clear. I got too many thoughts going on.

It will be the final hull.

I can always go back and make a mold from the plug if I’m not satisfied with the results. But so far it seams to be working fine.

for the final hull I would go with 15 oz of glass over the entire hull.

Dansherman,

I’ll add another layer of the 3.6 oz. that will put me at 12.8 oz.
Thanks again for all the assistance. I’ll keep posting on my progress.

15 ? - or did you mean 1.5 ?

I don’t think my “real” catamaran had that much glass on it.

I have seen IOMs made from as little as 2 layers of 4oz cloth (8oz total), and as high as 3 layers of 6oz (18 total). Since he is using an epoxy that is not specifically designed for laminate construction I would lean towards the heavy side, say two layers of 6oz and one layer of 3oz.

I still need to do some sanding but I’m getting close to priming and sanding.




The iniquity of model yacht rules.

Back in the late 70s, our Pscesetter 28 half-tonners (28.5 feet LOA) used 2 * 1.5 oz. CSM eiher side of a 1/2" balsa core. Apart from keel and mast loads, internal reinforcment was 2 ring frames at centres of about 9 feet. As far as I know, all but one of the 20 boats built using this structure is around today in decent condition.

The other went up a rocky beach in a gale. I think somebody is rebuilding her.