Delaminating repair

[gtflash]

I have bought a 28ft stepped hull, ex race boat. She has worked quite hard and is rumoured to have delaminated. Original construction was foam cored deck. To standard manufacturers layup, and hull was one layer less and derakane resin, foam stringers throughout and ply transom. The hull has been reinforced with a mahogany type wood, laminated over the top. The repairs are a little obvious and I would like to tidy it up inside the hull. I have used polyester resins quite a bit as a hobbiest, and experimented with epoxys.

My intention is to feather or remove some of the patchy hull repairs and overlaminate to add extra strength and weight. IT'S a very light boat for it's size. Possibly remove the wood and reinstate the foam stringers.

Questions are, what resin can I use to derakane layup, if laminating over the wood roughy how many layers of glass would I need to reinforce the stringers, could I install a foam core in the hull and overlaminate to create a strong sandwich, or could I use carbon fibre to add extra strength, or would it not stick well or create prsssure between differing materials.

All delamination occurred in the hull, but she appears reasonably sound now, just not very pretty down below. Hull outside is as straight as they come

[Petros]

Using graphite is not necessarily stronger, it is used to save weight (use less of it to achieve the same strength), you can acheive the same strength with more layers of cloth, and it would cost much less than graphite too. Also graphite composites are much stiffer than fiber glass, so I would not think it would be a good idea to mix materials, however the adhesive resin is the element that does the bonding, not the type of fiber in the matrix. If it was built of glass fiber and epoxy, than that is what you should use to repair it.

Using a foam core will make it stiffer and stronger (the more distance between the outside and inside of the hull, the stronger it will be), or it would weigh less for the same strength since less cloth and resin would be required. It would be adviable to make it stronger since it will prevent the same damage from occurring again in the future.

There are others on the list that can give you more specific information on the details of the repair for I am not familiar with your hull configuration.

Good luck

[gtflash]

Thanks for feedback. Is derakane a epoxy type resin? If I am unsure if rather stick to epoxys as they appear to stick very well. How many layers of cloth would I need over a foam core? That is my preferred option.