Soft spot & gelcoat repair questions (1968 Highlander 20)

[daniel.kringer]

To any who could advise! I am planning to do small soft spot & gelcoat repairs on a new to me 1969 Highlander 20. I am unsure of the hull construction (built in the 1960s). Up to this point this most I've done was a repair on a Hobie 14, which I understand has two layers of fiberglass with foam core in the middle. For that I Drilled holes through the outside layer and filled with polyester resin. Can I just follow the same process for the Highlander 20? Is the construction fundamentally the same? Having trouble find info online on the boat's construction. I heard that some older boats have a different approach to fiberglass layering.

Video of the soft spot linked:

1969 Highlander 20 Soft Spot

youtube.com

 

[Foswick]

Well, I would treat the idea that it is indeed a soft spot with a little skepticism until you get some more information. It would be uncommon for the hull to be cored. I would expect it to be solid fiberglass. So, the tapping sound difference would be due to something else.

That said, I ran across this: https://sailingtexas.com/201901/shighlander20109.html

The owner talks about an area of balsa core behind the swing keel trunk that needs repair. So, maybe.

More information is needed, and ultimately, you might need to bore a small hole to inspect (though that would not be my next move). But, if the core is indeed wet, that is a fairly involved repair. I have no experience with such a repair in the hull because, as I said, it is typically all-fiberglass down there - at least on boats I have seen or worked on.

Elsewhere (like on the deck), such a repair often involves removing one layer of fiberglass, revealing the damaged core but leaving the other fiberglass on the other side intact. Then, clean out and replace the damaged core, replace the removed fiberglass, sand, etc.

To be clear - I do not know the preferred way to make such a repair in the hull. I would think that it would be preferable to remove the fiberglass on the inside, likely being thinner and less fussy cosmetically. But, access inside is likely an issue. There will be someone here that has more experience with this than I do.

But ... again ... I would do a little more investigation to ensure that is indeed the problem. A moisture meter could help. The next step might be to drill a small (1/4") hole in the middle of the area, being careful to catch whatever comes out of the hole. Water might just drip out, and that would tell you something. But, it should also give you some idea of what else is in there and whether it is wet/damaged. If you do this, take some care to pay attention to what is on the other side of the hole before you drill. A hole that size is easily repaired.

 

[daniel.kringer]

Thanks so much for the reply!

I called Allen Boat Co., which manufactures the current highlander. They told me that for this model, the hull is indeed all fiberglass with no core. The deck is wood - which you can't see in the pictures. Behind the spot in my video, on the interior of the cockpit, there is a storage compartment - a molded shelve which comes to about halfway up the interor of the bow, so there is not direct access from the interior.

I would guess if there is no core, that there is potentially an issue with the laminate losing its integrity? As far as I can tell, it's limited to that particular spot - will be flipping it over this weekend to take a better look at the rest of the hull, and try to repair the gelcoat.

My understanding is that the fix for this is difficult, if the fiberglass is compromised! Any thoughts welcome, and thanks again!

 

[Foswick]

I would guess if there is no core, that there is potentially an issue with the laminate losing its integrity? As far as I can tell, it's limited to that particular spot - will be flipping it over this weekend to take a better look at the rest of the hull, and try to repair the gelcoat.

It is possible for the fiberglass to delaminate, but that would be fairly uncommon. Look at the location and see if it coincides with likely stress from a grounding or a place that it might rest on the trailer - some indication of how that location could have been subject to particular stress. You can also, for example, have an issue with the original layup having a small resin-starved area that can cause some issues down the road.

This gets a bit out of my wheelhouse. But ...

I would use a screwdriver handle or something to sound the hull and determine the exact size, shape, and location. (You've probably already done this.) Then, look inside and look for things like delaminated tabs. Or, you might find that whatever is attached to the inside of the hull explains the difference in sound, and there is no defect at all.

If you do have a structural problem in solid fiberglass below the waterline, you are right - the repair is not trivial. But, you might just decide to live with it - depending on whether that location is really a problem.

Where is the spot, actually?

 

[JBP-PA]

The video only shows a difference in sound, not a soft spot. The hull sounds different at a bulkhead, which is perfectly normal.
The video also appears to show some large stress fractures in the gel coat. If you push in the hull, does it move easily?

 

[daniel.kringer]

The video only shows a difference in sound, not a soft spot. The hull sounds different at a bulkhead, which is perfectly normal.
The video also appears to show some large stress fractures in the gel coat. If you push in the hull, does it move easily?

Hiya thanks for the note! Yes when I push on that spot it flexes much more than the surrounding area. I'm going to have a look at the opposite side to see if there's something similar in the same area or not. In which case maybe it's structural!

I wish I could find more info on the boat's build - not much online!