I think Paul is right, this seems like a nightmarish place to mix wood and steel.

If the reason you didn't want to use steel was that you don't have welding equipment, most of the expense comes from the fit-up, not the welding.  If you cut all the steel yourself and have the surfaces cleaned back to bare steel, and the new pieces test fit, then the number of hours you need a welder for the actual welding is usually a manageable cost for a project like this.

Nicholas,

here is how I made a set of new  cockpit hatches for my Johanna, back in 1999. Johanna was an owner-finished version of the Alo28, so the hatches of this boat had been glued together from thin planks. With the glue failing, all the hatches were about to fall apart, and of course leaked a lot.

On  taking a closer look, I found that the hatch openings had been well made with a moulded ridge and then a groove around it to drain away water. I therefore made the hatches from plain 15mm plywood. Instead of trying to make them as tight as submarine hatches, I simply skipped fitting gaskets. Instead, I made a simple ‘drip lip’ from Sikaflex, running continuously along the edges. See diagram and photos below.

Having never seen this in use before, I tested it by laying old newspapers inside the cockpit benches (-trunks?). Paper from newspapers not only tells if it wet. It also tells if it has been wet. The result was perfectly good  -  dry newspapers. Maybe you can pick some ideas from this and use on your boat.

I don’t claim that this will keep out all the water each time the cockpit is filled up (how often does that happen?), but if strapped down, they should only let in a few drops now and then.

About making the foot well smaller: What about tailor-making one or two trunks which you secure in the foot-well? These will take up volume there, and in addition they will add storage space. I would of course have made them with the same sort of simple plywood lid as mentioned above.

Good luck!

Arne

My yacht is a construction of steel hull, decks and cockpit with ply and hardwood cabin coach roof. I now wish to address the replacement if her failing plywood cockpit locker lids which are poorly designed and incapable of being adequately secured againt water ingress. At the same time I would like to reduce the volume of the vast footwell so far less water will be held in the event of a wave jumping in.
I have looked long and hard at the current arrangement to see if some improvement to these may be sufficient. I have concluded that the best way to procede may be to line the cockpit with plywood so that new locker lids can be made more easly and simply than attempting a retro fit. I have found pictures of a double coaming type as used on wharram catamarans that look simple enough for me to build and will be easily secured and watertight. The ply lining would also make it easier for my limited skills to install storm boards or a footwell box for liferaft storage or similar.

So the point of this ramble. There seems little clear info or consensus on the best way to bond the two different materials. I understand the issue is about rate of expansion and contraction. Does anyone have knowledge or experience of doing this type of thing or have any recomendations as to how to achieve a high strength bond and seal between the two long term? Are there any better desgns of locker lid that I should consider?

I have some other repairs to make at the interface of the two materials which will require the same type of bonding and sealing so keen to find a permanent high quality way of effecting these.
Your thoughts will be most appreciated.

Nick