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Please offer advice on the repair of the Unibond hull of my 1970 11-footer, and specifically for the repair of the damage seen below in Figure 1.



The hull has a crack along the chine line forward of the patch (seen in Figure 1 above). The original fiberglass layer is thin or missing. Some hull foam is exposed.


BACKSTORY
I started the restoration of my 1970 11-foot hull with the hull bottom. I have made three repairs so far, and I have more repairs started and in various stages. Repair of the area seen in Figure 1 above has not been started because I think I could benefit from more practice. Also I could benefit from having a real game plan.

The area appears to have a pre-existing repair in this location. The hull has a crack along the chine forward of the patch. The original glass is thin to gone and there is a bit of exposed foam superior of the patch on the side.

Q1: what product is your favorite product to use to make structural hull repairs to a Unibond hull?

I've been using [a product only identified by the number] 1708. However, three layers wet seem to be all I can do given the thinness of the hull. It's less [a problem] on the bottom. On the interior I expect [using three layers] will be a cosmetic problem: three layers will almost inevitably end up as high areas.

kassak wrote:Please offer advice to me on the repair of the Unibond hull of my 1970 11-footer, specifically for the repair of the damage seen below in Figure 1.

Advice for making repairs to the Unibond hull of Boston Whaler boats is offered in a pinned article at the top of this forum. See

Advice on Repair of Unibond Hulls
https://continuouswave.com/forum/viewto ... f=6&t=9254

kassak wrote:Q1: what product is your favorite product to use to make structural hull repairs to a Unibond hull?

I prefer to use WEST Systems epoxy resin to make repairs. Epoxy resin is a stronger adhesive when making secondary bonds to existing polyester resin laminated hulls. For more advice on using epoxy resin to make repairs to a Unibond hull, listen to my interview with Jim Watson of WEST Systems at

Whaler Radio (or Podcast)
https://continuouswave.com/whaler/radio/

Part One of my interview begins at
https://continuouswave.com/whaler/radio/media/westPart1.mp3

Part Two continues at
https://continuouswave.com/whaler/radio/media/westPart2.mp3

Note: the Whaler Radio interviews began in the year 2000, before the term "podcast" had been invented.

Specifically in regard to the damage seen in Figure 1, the advice offered in the Boston Whaler literature should be used, following the advice given in example 4, "Structural Repairs." See

INSTRUCTIONS -- HULL PATCH KITS
https://continuouswave.com/whaler/refer ... tions.html

The above article reproduces in HTML the printed instructions distributed by Boston Whaler to owners in 1994.

A good example of hull repair is shown in a Reference Artice that provides an illustrated narrative of making such a repair at

Repairing Hull Damage the Whaler Way
by Taylor Clark
https://continuouswave.com/whaler/refer ... epair.html

When making hull repairs to areas of the hull that will be below the waterline when the boat is in use, the concern for a perfect color match to the hull existing gel coat resin appearance can be moderated somewhat, as the repair area will not be in plain view.

Thanks for the reply.

I've read all those articles.

What I was looking for was more advice on how to manage all the various angles and planes coming together. Once I grind off the old repair there is going to be a lot of missing fiberglass across lots of surface. I am imagining that a single large pieces of glass and successively smaller pieces is going to struggle since a 2D surface will struggle to lay flat against the complex 3D surface.


In terms of product preference, I was asking about the fiberglass cloth folks like to use to meet the hull thickness.

Thanks,
Steve

Generally the hull should be symmetrical about the centerline. If the area of the hull opposite the damaged corner seen in Figure 1 is in original condition, you could make a template of the hull shape from the undamaged side. The template could be used to guide the repair of the damaged side.