filling IOR voids and bumps

any suggestions on what would be the best material to fill the "rule beating" voids on an IOR design? i want to fill the in the stern where the IOR rule encouraged pinching in the stern. the void, if you follow the natural hull lines, is aprox 3" deep X 8' long X the width of the boat. west system microlight won't work because my hull will be red and i not sure that microballoons will work because of the weight(of material) and the thickness (3").

if any one has experience with this type of modification, i'm open to any suggestions.

thanks....dave

 

I recently filled some hollows on the inside of a racing yacht hull. The technique I used was expanding cavity wall foam, cut down with a wire brush disc on a drill. On top of that you can use a layer of micro-filler (most types) to smooth the surface, then put a layer of glass fibre over it to waterproof it.

Bear in mind that you may need to build a mould first. Also, the expanding foam can exert quite a force. Could you invert the hull? it would make the whole job a bit easier.

I know this method sounds rough and ready, but take your time and it will produce a pretty good result. Final finishing can be achieved by putting a thin layer of woven glass on, then finishing with resin/filler and an appropriate coloured paint.

Hope this Helps

Tim B.

 

You can glue a sheet of dyvinicell or other structural foam, shape it and glass over.

 

i thought about this method, but because of the compound curves i'm guessing that i would have to use strips and not sheets.

thanks for the advice...dave

 

what a great idea. i can't invert the hull, but i'm thinking that i could build a mould out masonite or some other thin smooth hardwood. it would also seem that the mould would not need to be exact since the foam is easily shaped, is this a correct assumption?

i'm guessing that the foam won't offer any structural strength unlike corecell?

thanks for the help....dave

 

What did you use as a mould release? I'm concerned with my finishing (outer layer) layer of glass sticking to the foam.

thank you, dave

 

I left the foam in, since I was only doing a fillet along the floor/centreboard. The foam is very light anyway, but if you want to use it as a mould, wrap the moulding surface in clingfilm (yes, the kitchen stuff for packing food) then the foam won't stick to the cling-film very well, and the cling-film won't stick to the hull (well, no better than you would expect), I would personally leave the foam there for the support and then skin it with some glass or carbon cloth (or chop-strand-mat) with a finishing layer over that.

Cheers,

Tim B.