Hobie 18 Deck Repair (Soft Spot)

I know, I know... another soft spot topic from SabresfortheCup!? How can it be!?

I'll keep it short. Found a soft spot in the deck of my port hull, just forward of the rear crossbar (where the skipper sits), probably a good foot long, and almost that wide (probably about 3/4 the width of the deck). I know it's a common spot, and I'm already warming up my epoxy! I've read about others reinforcing this area with under-deck bulkheads. My question is, if the inner layer of fiberglass is intact, are the bulkheads necessary, or will a simple epoxy repair likely cover it?

I'm still astonished at how quickly these things develop. Last year, I thought it might've felt a tiny bit spongy, but I wasn't positive. Thought I might be paranoid. This year, it's large enough that pressing on it with about 30 lbs of force with your palm is enough to feel it move.

EDIT: *Correction... pressing on it with your thumb with about 5 lbs of pressure. When these things get soft, boy do they ever go soft!

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Mike

'79 H18 standard 'Rocketman II' sail #14921 RIP
'78 H18 (unnamed) sail #14921
'08 H16 sail #114312
'97 H21SC sail #238

Epoxy done correctly is all you need. Bulkheads won't cure delamination.

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thanks Matt! I wasn't looking forward to trying to figure out bulkheads, anyway!

The bulkheads won't cure the delam, but they will greatly reduce the flexing. Repetitive flexing is what ultimatley causes delam in that area - the skipper stepping on the deck coming in off the wire, etc. Putting in the bulkhead would make the deck even stronger then original. I would start with the epoxy injection, but keep the bulkhead idea in your back pocket if you aren't satisfied with the results of the delam repair.

The other question is how do you know the inner layer is intact?

sm

Good points srm, I'll keep that in mind. Given that this is soft spot #3 in this hull (and #4 overall), I guess I'm starting to wonder how much longer the boat is going to last, and trying to consider how much work I want to keep putting into a boat that may not last me another 5 years. I don't know, maybe it'll last another 10, or maybe the hulls will blow out in 3. Hard to say, but at a soft spot per year, it seems to be on the decline. Gets kinda discouraging after a while when trying to restore & maintain one of these old boats. Shame they couldn't make 'em bullet proof, eh?

To your second point, I don't know that the inner layer is intact, it's only a supposition. I'm hoping it's still intact, as the spot just appeared on me and I haven't really put much weight on it, but you never know. I figure if it isn't intact, I'll probably need to put the bulkheads in anyways.

As sad as this sounds, you are correct. Once delam starts to pop up randomly and all over you are witnessing the structure and adhesive bonds breaking down. Assuming your decks and hulls forward of front beams can be kept solid you should be safe to sail the boat. The older boats seem to get "rubbery" all over the place and people will keep sailing them until the boat snaps irreparably, especially on inland lakes.
Advice? Keep your eyes peeled for a late 90's early 2000's boat and/or hulls. Start putting a savings together for a newer boat. Especially if you're into racing :0)
I have a great condition Hobie 18 in my back yard that's getting soft spots like yours..... It's retired until I luck up on a parts boat with good hulls. In another year or two ill sell all my good h18 parts ( all fresh water, great cond, 1yo mainsail, 5yo job perfect mast ect ect.

Unfortunately you need to go to Europe to buy a new Hobie 18. Hobie Pearl or Hobie tiger are the closest.

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Tim Grover

Memphis, TN fleet 134
Hobie 20! G-Cat5.0 and 2 Hobie 14's
Photobucket now wants $100 to post pics on forums......... pass.

Fxloop, that's my fear. So far it seems that all my soft spots have been in relatively high traffic areas (aft of the rear crossbar - both hulls, inboard side of the port hull alongside the daggerboard trunk - where you'd stand to right the boat, and now forward of the rear crossbar, port hull), so I'm hoping that is the primary cause, but I guess if the bonds between resin and foam were breaking down, that's exactly where it would start anyways. Shame, I just spent an entire weekend buffing all the oxidation out and polishing up the hulls.


Here's what I found when mapping out the soft spot. Quite a bit bigger than I had initially thought. We'll see how the repairs go.

that is exactly the size and location of the soft spot on my H18.
I found when injecting Git-Rot resin for the repair, the lower layer of fiberglass was split open allowing the resin to wind up on the hull's bottom. something to watch for.

fortunately there was still enough mold release residue inside that I was able to pull the resin out.

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Chris
'88 H18SE Arís

Thanks Chris, how long ago did you make the repair? Are the hulls still holding up well?

I put a video camera (iPhone) in through the rear access port a few times during the repair. No splits or leaks through! However, it would seam that I have two separate issues going on here. The first is delamination, which was maybe about 2/3rds the size of the area identified in the picture. The second is perhaps softening of the foam core. I drilled holes around the inside of the perimeter I had identified and, though that area was slightly spongy and moved with a fair amount of force, the perimeter holes did not actually breath out and fill with epoxy. I had to drill new holes, closer to the softest part of the spot to actually evacuate the air and fill the void with epoxy.

The separation was once again between the inner layer of glass and the foam core, which seems to make it very difficult to identify the exact outline of the soft spot and to drill within that region.

so the idea of all the tape is to keep any extra epoxy off the hull?

Exactly. When you inject the resin into the hull, it will ooze out of the adjacent holes in the deck. Without the tape, the epoxy will make a mess in the non-skid.

sm

What's worse is that it yellows/darkens in the sun, so those spots in the non-skid that are barely noticeably at first become painfully obvious a few years later, like the non-skid is always dirty. No way to clean it out.

I'm happy to report that the spot has hardened up nicely. Seems harder than it was originally! I think that, where I had thought the surrounding area was spongy, it was actually just suffering from the lack of support from the soft spot, as it's plenty hard now. Now I just need to drill out the holes slightly and fill with some gel coat to hide the repair!

so i take it then you drill all your holes before starting to inject.

That's what you want to do, yes. Unfortunately in this case, some holes were outside the soft spot and I had to re-drill while injecting to try and fill the entire void.

Here's my procedure:

The first thing I do is tape of the area and then carefully press or tap on the soft area to try and identify the outline of the soft spot. This can be a little tricky, as it's not always a clear line. There can be a little guess work involved. Then I mark my holes every inch or two along the perimeter, just on the inside of the line. Put one hole in the center (and only one). The difficulty that I always run into is that you want to make sure you get your holes as close to the edge of the soft spot as possible, but inside the soft spot. If you drill them too far out, you'll miss the soft spot and the air & epoxy will be trapped and unable to escape.

Once all my holes are marked, I take a small drill bit (I think I've been using a #31 or 1/8" bit) and carefully drill through the gel coat and outer layer of fiberglass, with very light pressure. Once you're through the outer layer, stop. You'll want to very, very lightly drill through the foam core (but not the inner layer of fiberglass). I'd recommend just twirling the drill bit in the hole with your fingertips, that should do it.

When I've got all my holes drilled, I mix my west systems 105 epoxy, 206 hardener and filler (I use 404 for high compression areas, or 408 for lightweight areas). I usually mix about 5 pumps of epoxy at a time. This soft spot took me 10 pumps total. When mixing the filler, I want to keep the epoxy thin enough to flow through the soft spot. I typically go for a syrup-like mixture. Then I just start injecting the epoxy into the center hole with a syringe, and let it flow out towards the perimeter "breather" holes. I find that it can be helpful to press on the center of the soft spot a few times after a while, using moderate pressure, to "pump" the epoxy towards the holes. When epoxy starts flowing from a breather hole, I cover each one with tape to direct the epoxy towards the next hole in turn, until the entire soft spot is filled. I then remove the tape and let it ooze out freely, wiping it up occasionally, until it hardens. It allows the surface of the deck to even out a little.

Once fully cured, I remove the tape and take a chisel or sharp knife to cut the epoxy "plugs" flush. I could call it quits there, but I prefer to try and hide the soft spot repair, so I drill the holes back down slightly with a somewhat larger drill bit and mix some gel coat paste to match the color of the surrounding gel coat and fill in the holes. I'll have to use tape for the ones in the non-skid, as gel coat in the non-skid makes a mess. Once that's done, I'll probably have to lightly sand down the holes (800, 1000, 1200, 1500) and buff out the scratches.

Sabres,
I have yet to affect the soft spot repair this year after last year's attempt. Hope to get to it in the next couple weeks.

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Chris
'88 H18SE Arís