Repair of *lumpy* bottom from trailer damage

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Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Tue Nov 27, 2012 12:05 pm

Hi,

Just got a DS1 that has been sitting for many years on a trailer and is large lumpy deflections in the bottom.
Anyone fixed this type of issue before?

I'm not worried about glassing, etc.. I have plenty of experience there - just not sure of the approach.
In fact - we may have found another hull only boat I could cut the bottom out from the centerboard back and replace this bottom.
Just wanted to check if anyone has fixed this before.

Let me know,
Thanks!
Bob Perkins
 
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Tue Nov 27, 2012 3:06 pm

Hi Bob,

I did that repair on my boat. It’s likely with your boat, as it was with mine, it is soft from the trailer damage. I think it’s not only from just sitting on the trailer but from bouncing on an improperly supporting trailer. That flat section behind the centerboard and in front of the transom is definitely where most of my problems were. But performance wise, it’s one of the more critical places on the boat, at least if you’re trying to plane. Though, I felt that my boat could use some stiffening of the hull forward of that, as well. What I did was put in a structural foam core. This gave me a nice stiff hull to work with and then I fared it with epoxy/micro balloons and fairing compound. Yes it was a lot of work, but the boat is night and day better performing. No, I don’t race but I am enthusiastic sailor and like a nice responsive boat.

Have you considered whether you might be better off using the other hull? If that one’s pretty straight and not too soft it might be easier doing cosmetic work and moving the hardware over. If it’s just mildly soft you could run additional stringers.
KC Walker, DS 1 #7002
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Tue Nov 27, 2012 4:24 pm

Amazingly - the boat is in very good shape.
It appears it had been stored indoors for the last 25 years and not touched.
No bouncing or even use. This is the only DS I have ever seen w/o cracks at the cabin top corners and had not been repaired.

I think it had just been sitting on rollers and it warped the big flat area and somehow finally busted through.
From the rear of the CB Trunk forward is fine. Nice hull in fact.

My thought is if the boat that is just a hull has a nice bottom between CB and transom - I can cut it out and replace the busted up one I have.
Like Corvette repair...
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Tue Nov 27, 2012 9:02 pm

Bob,

If you’re familiar with doing Corvette type repairs, this should be a piece of cake. If your present boat just has roller dimples, I wonder if you could heat them with a heat gun or heat lamps and press them back out? If you didn’t press them all the way out you could then grind a bit of gelcoat away and put some biaxial stitch mat inside and outside. This would stiffen those spots considerably and hold them in place. No matter how you approach this you are going to end up needing to do fairing and painting, so this might save you some time and aggravation of lining stuff up. Using wooden battens works very well as guides for faring. You can really see what’s going on and where the low and high spots are. This article I found helpful http://www.westsystem.com/ss/assets/How ... ishing.pdf .

My guess is that you will find the hull only boat isn’t exactly perfect in this area. After all, almost all of these boats have spent time on trailers.
KC Walker, DS 1 #7002
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Re: Repair of *lumpy* bottom from trailer damage

Postby swiftsail » Wed Nov 28, 2012 12:06 am

Another method to keep from filling so much is to through bolt a 2x8 on each side on the outside. Then foam core the inside and fill the bolt holes left behind.
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Wed Nov 28, 2012 12:16 am

Swiftsail, that’s a really good idea! I wish I’d thought of that one when I did my core project.
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Wed Nov 28, 2012 8:59 am

We thought of that one too - use 2x8 on outside and pill into shape as best as possible and then use that as the starting point.
All good ideas - Just wanted to be sure I wasn't missing something obvious ;)
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Re: Repair of *lumpy* bottom from trailer damage

Postby Mike Gillum » Wed Nov 28, 2012 12:57 pm

Another method is to reverse what caused the deformation by flipping the boat over, point loading by applying pressure to the center of the deformation, taping a black vinyl garbage bags or a tarp over the area and using the sun to heat the area while checking from periodically making sure that you're creating an even bigger problem in reverse.
It'll still require coring or reinforcing the bottom after the deformation has been removed.
I would certainly recommend that the trailer either be upgraded or replaced before going to the trouble of fairing or rebuilding the bottom.
When I picked up #2772 six years ago it had been sitting on "EZ-Roller" trailer all of its life and the bottom looked like a really large potato.
I replaced the trailer with one that has a full-length indoor/outdoor carpeted 2x6 centerline support that ends about 3' in front of the transom and goes forward past the bow along with a pair of carpeted 1x6 with 2x2 side supports that align with the vertical face of the seat tanks and are 1/8" below the hull so all of the weight of #2772 sits on the centerline support.
My original intention after replacing the trailer was to core, fair and refinish #2772 but other than wet sanding, polishing and waxing #2772 I'm really hesitant to screw with a boat that won 2011 & 2012 DS NACR's!
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Wed Nov 28, 2012 1:08 pm

Yes - The trailer is getting a major update.

Our other boat (3544) has a nice bottom, trailer and the works.
This method of using heat to try to un-deform the bottom is interesting. I will have to look into that.

Researching the foam core (which 3544 has) has shown that the Divinicel (sp?) is pretty expensive.
Any recommendations on thickness? or other core materials?

I'll post some pics soon
Bob Perkins
 
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Wed Nov 28, 2012 2:19 pm

My boat was on an EZ-Loader roller trailer and the point load definitely made the dimples in mine. I also went to wide full-length carpeted bunks down the centerline. My bunks are separated by about 2 inches and it’s amazing how well the boat tracks onto the trailer when pulling out. I used Corecell. I bought offcuts from Noah’s http://www.noahsmarine.com/index.asp?FS ... Featured=1 . They don’t always have the same inventory so it’s worth watching. I got the slitted kind which makes it easier to conform without heating it up. It’s supposed to be the latest and greatest high-tech core. I used 10 mm and the boat is extremely stiff now. The core itself weighs very little, it’s the adhesive and the other layer of glass. The thicker the core the stiffer the panel, though I doubt any more than this would be noticeable. I would not be surprised if 5 mm would be enough. I figured the difference in weight between 5 mm and 10 mm was negligible.

I felt like my boat was not stiff enough and that’s why I went with the core. Mike has a good point, though. Putting a core in does add some weight. If what you’ve got is stiff enough, after straightening, stringers could take care of it and you might not need the core. Keeping the boat as light as possible is a big part of performance.

Mike’s technique sounds good, though I’m sure it would work better in California than Connecticut, I have 34° today. I wonder if a combination of techniques could be used. You could use thinner battens, like 2 x 2’s screwed to the outside of the hull, maybe even 1 ½ “ square. This would keep it from going too far using Mike’s technique. If you weren’t getting enough heat from the black plastic you could always try heat lamps or heat gun.
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Wed Nov 28, 2012 2:27 pm

Core-cell - that is much better pricing.
I'll look into that.

We just got the boat 3 days ago - it is already flipped and off the bad trailer.
This discussion has been very helpful. I've done quite a bit of vacuum bagging - the plan would be to vacuum it all up to reduce the weight by keeping epoxy use to a minimum.
Thanks for the info.
Bob Perkins
 
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Wed Nov 28, 2012 2:52 pm

A standard practice with yacht makers using CoreCell is to radiant heat it to make it conform to the hull shape. If you didn’t mind doing that, you could heat smaller tiles of non-slitted and fit them together, if you did just between the seat tanks you’d be adding minimal weight and making a huge stiffness change. Vacuum bagging would definitely be the way to go. If you did that and then put in a column between the keelson/centerboard trunk and the cuddy (like Mike’s), you’d have a nice stiff race ready hull, ready for fairing.
KC Walker, DS 1 #7002
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Re: Repair of *lumpy* bottom from trailer damage

Postby K.C. Walker » Wed Nov 28, 2012 2:59 pm

Bob,

I just remembered who you were. You did some nice refurbishing on another Daysailer, and of course you showed some of your beautiful wooden runabout work. You sold the other Daysailer, for what I thought was a very reasonable price considering what you had done to it. Does this one looks like it’s going to be a keeper?
KC Walker, DS 1 #7002
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Wed Nov 28, 2012 4:18 pm

Yes - we sold 3303 in very good shape. We faired the bottom and painted, etc..
Then we got a race ready boat (3544) and sold the other one (at a bit of a loss - and especially if you take labor into account).

Probably should not have sold the other one - which is how the new one (1638) came into being.
That said - we have a collection of DS parts building and plenty of new expertise.
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Re: Repair of *lumpy* bottom from trailer damage

Postby Bob Perkins » Wed Nov 28, 2012 4:20 pm

Mike Gillum wrote:My original intention after replacing the trailer was to core, fair and refinish #2772 but other than wet sanding, polishing and waxing #2772 I'm really hesitant to screw with a boat that won 2011 & 2012 DS NACR's!


Mike - Did you end up with any stiffening of the floors? or is it just original? How about side to side or vertical stiffening at the cuddy? Those are some of our next projects to experiment with..
thx!
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