Hull: Repair Soft Spot

[BobBill]

Reinforcing advice.

On dinghy. Soft spot (worn thin) just behind dagger trunk center of hull.

Roving under glass cloth, epoxy matrix or plain cloth with some carbon to stiffen a bit, epoxy also?

Area about a foot overall including good adjacent hull.

[bistros]

Originally Posted by BobBill

Reinforcing advice.

On dinghy. Soft spot (worn thin) just behind dagger trunk center of hull.

Roving under glass cloth, epoxy matrix or plain cloth with some carbon to stiffen a bit, epoxy also?

Area about a foot overall including good adjacent hull.

Depends on core construction, materials used and future use of the hull.

If the hull is cored, you may have to remove damaged core and replace. Wet and soggy damaged core (foam, wood, whatever) will spread and get worse, no matter what surface patches are applied. Wet and damaged core can raise hull weight dramatically - it isn't unusual to find 20 pounds or more water in a damaged foam core. Drying time and getting the water out is an art.

Class rules may limit materials that can be used, and if keeping the hull legal and measurable is an issue, you have to consult the class rules.

Generally, some attention must be paid to the original construction - epoxy does work well on polyester if a mechanical bond is enabled, but polyester does not work well on epoxy. Consult the class association for help, or the original manufacturer if they still exist. Posting pictures here will help a lot.

Certainly, patching with stiffer materials may end up with a better result, but if a future purchaser of the boat is thrown out of a regatta due to illegal materials used, you may have to be careful what you represent the boat as. A 29er ceases to be a 29er if carbon uni is used in a repair with epoxy.

--
Bill

[alan white]

What is the boat made of? Plywood?

[BobBill]

Sorry. Boat is all Glass, inner and outer hull config.

No core, plain lay-up with stiffening via deck section.

Here is pic, although not the exact same boat.

[gonzo]

Mat and polyester should do fine for a boat like that. You can use stich mat if you want to build it more.

[BobBill]

Thanks Gonzo, looks like a good idea, maybe with Steve Clark's suggestion of using pipe insulation glassed in (carbon assist maybe) for strength...another great idea that I never would have thought of.

You gents have my brain working anew.

Here (finally) is a pic of actual spot. It is mostly wear damage. Add the munch from being soft that needs attention and some stronger backing as noted for careless dagger board grounding. No biggie.

Very much appreciate the advice.

[gonzo]

I can see a wooden block. Make sure it is really dry before you glass over it.

[BobBill]

Gonzo, Thanks, been away doing basketball stuff.

I don't think wood block present, but if so, I will replace.

The plan is to replace or install wood or composite backing for all hardware such as mast yoke, bow eye (new), traveler track, etc, even transom, add access ports, clean out and fix soft spot and smooth a bit, rejoin deck and hull, and refinish the little boat's deck and hull.

Getting close to begin date, after NCAA madness.

[hoytedow]

BobBill, this is a great thread with intelligent questions/answers, but the green ink is h e l l on my old eyes.

[BobBill]

Sorry! My screen is a bit off and I have a mild odd color blindness. But am buying a new Westinghouse screen today and will go with dark whatever. I have learned it makes finding the thread end easier, if I was contributing.

Will try dark blue.