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Soft spot prevention?
http://www.hobie.com/au/en/forums/viewtopic.php?f=13&t=52771		 Page 1 of 1
Author:  SabresfortheCup [ Thu Sep 04, 2014 11:03 am ]
Post subject:  Soft spot prevention?
Looks like I'm not done with the Epoxy quite yet...

I've found another soft spot in my hulls, this time on the port hull, inboard side, pretty much alongside the daggerboard trunk (well aft of the crossbar). Probably ~8-12" in diameter. I saw what looked like a large "bubble" in the side of the hull, pressed on it and heard that characteristic "crunch."
Image
Image Image

This seems odd to me. I know decks are common, due to the constantly compression from being sat on and walked on, but the side of the hull? This will be the third soft spot I've had to repair in the last 3 years, and the second one on this hull. Each soft spot developed fairly quickly, I believe... I don't think this one existed a few months ago, and it definitely didn't exist a year ago. The other (rather large) soft spot in this hull didn't exist two years ago, I'm relatively sure. Other than these problem areas, my hulls are in great shape; just some bottom wear and (I suspect) leaky deck ports... very little water in the hulls after a sail, sometimes even bone dry!

Here's a picture of the bottoms of my hulls from this June when I had it all apart:
Image


My question is, what could've caused a soft spot in a relatively low stress area of the boat, in such a short time period, and what can I do to prevent it? I believe that one per year is beyond random happenstance, and is more likely the result of a larger problem, either with the boat or with the way I maintain it.

I don't have a place to store the boat indoors, so unfortunately I keep it on a trailer (bunks), outside and uncovered year round, but I remove all the rigging and trampoline in the winter.
Author:  John Lunn [ Thu Sep 04, 2014 12:41 pm ]
Post subject:  Re: Soft spot prevention?
Yikes ! soft spots on the sides of the hulls?

Have you had any capsizes in rough weather, where you might have trod on the inside of the hulls?
I know that years ago, I dislodged the shoe of a H16 pylon that way when in heavy chop.

My old H18SE had the sail # 14937, same pattern.....
Author:  SabresfortheCup [ Thu Sep 04, 2014 12:48 pm ]
Post subject:  Re: Soft spot prevention?
A few capsizes, not many and not too bad... however, I've only owned the boat 3 years. It was supposedly in storage (in a shed) for 20 years before that, but the scrapes and scratches, and the condition of the bottoms tells me that she's seen some heavy use in the past.

That's pretty funny, John. Maybe they were only ordered a few hours apart! I'm rather fond of the pattern, I think I'd like to stick with something similar in the future.
Author:  kdj [ Sun Sep 07, 2014 7:39 am ]
Post subject:  Re: Soft spot prevention?
I've had the same problem, only with the starboard side. I put it down to the 30 year old foam/fiberglass bond just failing. I used the injection method to fix this spring and so far so good.
Author:  SabresfortheCup [ Thu Sep 11, 2014 6:34 am ]
Post subject:  Re: Soft spot prevention?
kdj wrote:
I've had the same problem, only with the starboard side. I put it down to the 30 year old foam/fiberglass bond just failing. I used the injection method to fix this spring and so far so good.


That's kinda what I've concluded as well, 35 years is just approaching the limit of the bonding strength of the original polyester resin. I just figured that perhaps there were some contributing factors that may have hastened or exacerbated the issue, especially considering that this is a low stress area of the hull.
Author:  srm [ Thu Sep 11, 2014 6:58 am ]
Post subject:  Re: Soft spot prevention?
I think moisture ingress into the hull is probably a contributing factor. Best to keep the hulls stored indoors (ideal) or covered but with the port hole caps removed so air can circulate through the hull and ensure things stay dry. Store the boat with the bows tilted upwards so any water that does get in drains out.

Otherwise, cyclical flexing will eventually break down the foam core and/or laminate bond. Be mindful of how you step on the hulls and how they're supported when loaded on the trailer. Otherwise, the hull lamination/construction is a manual process and subject to variations (especially the older boats), some boats were simply built better and will last longer than others.

sm
Author:  wscotterwin [ Thu Sep 11, 2014 10:33 am ]
Post subject:  Re: Soft spot prevention?
Blue boats go soft the fastest. I know as I have had over 35 boat through my back yard over the last 3 years and have viewed 100s. Once the sides start going it seems to be over. It will continue and is part of a larger problem. Top decks can be repaired (professionally is best, Non injection) and they can hold up years more. We only repair H20s Professionally (to few boats).

I believe the colored boats absorb the heat more than the white boats. White boats go soft also but for every blue and yellow that is soft, only 1 in 4 white boats of the same years are soft. Most of the white soft boats I have come across have been from the California Valley areas where it is regularly very warm. 90-100+ degrees daily. The only blue boat (older than 1983) I have come across solid was from the cooler SF bay area and was stored inside.

I also believe the wax agent in the Poly was the culprit and haunted pre-1983 boats. You also see much fewer colored boats after 1983 for some reason.

Heat is a big issue. Keep them cool and dry. Shade if possible
Author:  SabresfortheCup [ Fri Sep 12, 2014 2:22 pm ]
Post subject:  Re: Soft spot prevention?
wscotterwin wrote:
Once the sides start going it seems to be over. It will continue and is part of a larger problem.


wscotterwin, are you suggesting that I'll be looking at complete delamination & hull failure in the next 2-3 years? Or is it a slower, more manageable problem that can be mitigated to keep the boat sailing for another 5-10?

I'm thankful that the delamination is alongside the daggerboard trunk, in an area that is both low stress and high strength. I assume a spot like this at or forward of the forward crossbar, or on the outboard side near the shroud anchor plate would be "terminal."

I'm assuming that by "professional repair," you're referring to cutting out and re-glassing the soft area, which is unfortunately hard to justify on a boat worth <$2,000... especially if the rest of the hull is likely to develop the same issue. Aside from that, it sounds like the best way to prevent them is to keep the hulls cool, dry, inside/covered and in the shade, or start looking for a new boat :shock:
Author:  wscotterwin [ Tue Sep 16, 2014 3:35 pm ]
Post subject:  Re: Soft spot prevention?
No set time frame. It will just be difficult to chase if it persists. I would be surprised if the boat is still real sound in 5 years.

It also depends on how you use it. If you sail them like we do on the coast of CA, Oregon Gorge, Mohave and SF bay.........hull failure is something we keep a close eye on.

If you are a recreational sailor on mild lakes, your boat may last for years.

wscotterwin wrote:
I'm assuming that by "professional repair," you're referring to cutting out and re-glassing the soft area,


On the soft deck areas of the H20s, we cut back the deck and repair the foam core. I wouldn't hesitate to do the same on my H18s that I race. It was to hard to find "my boat" not to repair it correctly.

Scott
Author:  moncasta [ Sat Oct 18, 2014 1:15 pm ]
Post subject:  Re: Soft spot prevention?
One thing to try is knocking on the boats more than pushing on the soft spots, you'll get a dull thud in a soft spot area, it only crunches once the damage has become so severe that the foam can crunch.

A note about H18 hull failures, the most typical catastrophic failures happen at the front crossbar, the bow breaks off at the front crossbar and tears out along both sides.

The value in repairing the hulls is also relative. In HI where they have fewer boats, you'll see all sorts of creative repairs. In CA we have a lot of the H18s kicking around and are more willing to junk those with lots of damage.

Good Luck.
Author:  SabresfortheCup [ Tue May 26, 2015 9:17 am ]
Post subject:  Re: Soft spot prevention?
Just following up in case anyone was curious.

I repaired this soft spot over the weekend. Turned out to be much easier after having done two on my aft decks previously. At least it was relatively straightforward this time.

I taped over the spot, marked and drilled the holes. One thing that I noted immediately was that the soft spot was caused by delamination between the foam and the outer layer of fiberglass, not the inner layer. My previous two soft spots had resulted from delamination on the inner layer. In one of those, the glass was not completely saturated with resin, allowing the epoxy to easily flow through it and into the hull, leaving a mess inside. (viewtopic.php?f=13&t=51574) The fact that the outer layer delaminated seems to be why the soft spot manifested as such a large, visible bubble or bulge in the hull. Once the holes were drilled, I could press down on the outer layer and depress it at least 1/4", as air whistled out the holes. Laying in the sun for a few hours, the glass seemed to settle back down somewhat, and I put some weight on it to help level it further.

Image

After mixing my 105, 206, 404 and 406 epoxy/hardener/fillers, and injecting a moderate amount into the center hole, I covered the center hole and pressed down. This very effectively flowed the epoxy out to all of the perimeter "breather" holes. I covered each one with tape as the epoxy flowed out, forcing it to the next hole and so-on. When all the holes had oozed some epoxy, I covered the entire area with painters tape to prevent the fiberglass from springing back up and sucking air into the holes. I further placed some weight on top and let it cure overnight. After removing the tape, the bubble appears to have mostly flattened out and the spot is solid again. Hopefully It'll be a while before I find any more soft spots in the side of my hulls, but it seems to me that the problem is just the failing adhesion between the cured polyester and the foam core. I'm sure it's only a matter of time before I find another one. What worries me is how quickly this one seemed to appear on me. I'm really curious how the bubble formed. Perhaps it was just from the air in the foam expanding in the heat, but you'd expect the bubble to "suck back in" in colder weather, which I did not see.

Oh well, I'll just keep on fixin' 'em and keep on sailin'! :D
Author:  srm [ Wed May 27, 2015 2:43 am ]
Post subject:  Re: Soft spot prevention?
That's also the exact spot where you would stand to right the boat after a capsize, so it's possible that the weight of someone on the hull flexed it to the point that delamination occurred. Sounds like you did a good repair, so just continue with the periodic inspection and all should be good.

sm
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