reducing weight on an old tri

I am rebuilding an old Hartly --Lively 28, ( as recognised by members on here) and am at the point where all the rotten ply is gone and new marine ply installed and re-sheathed in epoxy. I still have a long way to go and I am very aware of the weight of things.
On the outer hullsI have an aysemetric fixed keel made of steel which has some serious weight. I thought maybe if I used the keel to act as a former and laminate several layers of ply then sheath that, it would be less than half the weight. BUT (at last I get to the question) how thick would I have to make it to take the strain. I know that no one can give me specifices, but if i made it 30mm thck do you think it would snap off as I motored out the marina, or have I gone over the top where as a 6mm ply would do it?.
Also, Does anyone think that the aysemetric works? the keels are only about 2ft deep and 3 ft long wih a shaped leading edge I know in theory they should help But I dont think there is really enough leading edge to gain much lift from , and so maybe they are acting as a brake

cheers for any thoughts or ideas

Kim

 

Could aluminum possibly be a solution? Depending on the depth of the keel 30mm might not be stiff enough to resist bending. I'm just shooting from the hip here, someone more knowledgable will probably come along with some more reliable advice.

 

lightning an old tri

Hi TollyWally,

I have thought of the aly route but as you have reminded me, am now investigating the costs ( I must have had a few and forgot I had thought of that -----Cheers------ what was I saying! hic!!!)
The keels are only 2ft deep Max and about 3 ft long.
When I said 30 mm it could 3" thick, it dos not matter. If I can cut the weightdown I dont mind building in ply and resining over, its just a feel for what I might be letting my self infor.
If the loading is very high and I have to beef them up so much it would negate any benerfit. Thats the sort of adice I am Looking for.Its just seems daft having two hunkin bits o metal, just where the weight does not want to be if 2 bits of glassed over ply would do the same job,

Ideally I should chop out some dagger board cases, but I might do that next year as I have re-built 70% of the main hull and still got the outrigger arms to sort out and the season is not far away.

Kim