Hull Damage from trailer

[Swashbuckley]

From reading the forums I know this is a common problem on DSII's. Mine (Tiny Dancer DSII) was compounded by being left outdoors with the cockpit drains plugged. The boat was on a slope and held considerable weight on the starboard side for several years. In the second photo you can see the bunk marks on the hull. Can I get some feedback on this damage (if you can see it in the pic). Is it repairable? Should I leave it alone? Any help would be appreciated. Thanks, and the trailer will be rebuilt per group standards.

[GreenLake]

The case for leaving it alone would be that as long as the hull is watertight you can just sail it, albeit not competitively. And you would save yourself considerable work. If you plan on not doing any major work on the rest of the boat, and don't plan on trailering it far and wide and are generally a very casual user, I could see a scenario where "as is" fits in.

However, if you were planning a full restoration, then that effort would be wasted unless you also restored a solid hull.

With a DSII this is more difficult than with a DS1, because you can't easily access the inside of the hull. On a DS1 you could attempt to pull the hull into shape by screwing it into some battens, then reinforcing it from the inside. Unless you can separate the deck molding off your DS2 that seems an impossible repair.

You could build up the dents with light-weight filler (epoxy based) and then put a layer of glass or two over that so you get a new, fair, hull shape. The sandwich of old hull, filler and new glass will most likely be stiffer than what you have now, just from geometry, because it will the thicker. With luck, it may be about as stiff as what the hull was when new. (It will come at the expense of added weight).

A variation of the repair would attempt to add stiffeners working from the outside. (next post)

[GreenLake]

Now, if you could pull the dents out with a contraption like this:

HullBatten.jpg (25.01 KiB) Viewed 15146 times

a batten across the low spot and a bolt to hold the hull in place, and then somehow glue a stiffener on the inside, something like this:

Stringer.jpg (16.92 KiB) Viewed 15146 times

which would hold the hull in place and not let it snap back. That might give you a (nearly) flat and much stiffer hull, so fairing it would require less material.

On a DS1, this is easy enough do to, because you can work from both sides. On a DS2, it would involve cutting access holes. My thought would be that you could cut the access holes from the hull side in your case, the laminate is damaged anyway. If you cut something like an 8x8 access hole, you should be able to place two of these stringers on either side by reaching in. And you should be able to place bolts to pull the hull up to battens on the outside.

The stringers I would laminate on a work table. Two layers of cloth one narrower than the other as a base. Then something hollow like half of a paper towel roll. Bend over the edges or use some fillet material to make a rounded transition. Then cover with two layers of cloth, again one narrower than the other (to provide something like a soft transition - I didn't try to draw them separately). If you find this too flexible when it's done, add another layer of cloth over the hollow part.

Because the hull should basically be flat in those areas, laying up the stringers separately like this should work - depends on how well you can pull the hull back into a flat shape. Trying to laminate it in place would be much harder.

Then fit in place, glue with epoxy, and lightly wedge against the inner hull with foam until cured.

I'm suggesting a hollow shape so that these cannot retain water.

To fill the access holes, I would laminate a bit of a flat plate (3-4 layers of cloth) on a work table first and tapering the joints on both hull and plate glue that in. If the area is slightly hollow still after the repair, you'd have room to fit a final layer of glass over the repair from the outside.

Anyway, this gives you something to discuss and elaborate on.

If you are planning a full restore, the total effort to do something like this will be relatively small compared to fairing/painting and whatever else you need to do. But if you just want something serviceable on the water with limited effort, you might be better off with sourcing another hull.

[jeadstx]

Greenlake, you mention on the DS1 that you can work from both sides of the hull to add the stringers because the DS1 hull is exposed. Could the DS2 be repaired in the same manner by putting in maybe two 8" inspection ports on each side of the centerboard trunk in the DS2 cockpit sole. That would allow access to the bilge area without compromising the hull with any cutting. With ports in the cockpit sole they could be sealed when the work is done and provide a way to check on the work.

I know I've put two 8" inspection ports inside my cuddy cabin to have better access to the centerboard bolt. A secondary reason for the cuddy cabin ports was for additional storage low in the boat on the Tx200.

John

[Swashbuckley]

Thanks for the comments guys. Yes I have some thinking to do. I originally acquired this boat to sail the TX200. So at this point I do not see racing it. I expect it to be sailed hard and endure some damage. OK, so to restore it I would have to totally restore the hull shape. As a racer a DSII is not useable. As a former racer I want her to perform well.
Greenlake I like the info on battens. Thinking outside the box. What would be the effect of putting the batten on the outside? Performance wise? It would make it more durable for coastal sailing. I think the process you outlined would work great to restore the shape of the hull. The battens would stiffen and be sacrificial on beaching.

[Swashbuckley]

Tomorrow I am going to:
Step 1. measure the deflection.
Step 2. Look for any other hidden damage

Thinking harder on the fairing approach.

Appreciate the help guys.

[GreenLake]

Greenlake, you mention on the DS1 that you can work from both sides of the hull to add the stringers because the DS1 hull is exposed. Could the DS2 be repaired in the same manner by putting in maybe two 8" inspection ports on each side of the centerboard trunk in the DS2 cockpit sole. That would allow access to the bilge area without compromising the hull with any cutting. With ports in the cockpit sole they could be sealed when the work is done and provide a way to check on the work.

I know I've put two 8" inspection ports inside my cuddy cabin to have better access to the centerboard bolt. A secondary reason for the cuddy cabin ports was for additional storage low in the boat on the Tx200.

John, generally I would not be too afraid of "compromising the hull", because the areas in question are flat (or are supposed to be flat. It should be possible to close up any holes without compromising fairness or integrity of the hull. It will compromise the gel-coat, but after the kind of restoration we are being asked to look at, I can see a painted hull....

If having inspection ports in your cockpit floor is something that proves useful beyond this particular repair, then I cannot see much that speaks against them.

You would be limited to round ports, and you don't get the benefit of cutting out a bit of bad laminate from the hull It's great to have all the options on the table, @Swashbuckley will have to make the selection.

[GreenLake]

Thanks for the comments guys. Yes I have some thinking to do. I originally acquired this boat to sail the TX200. So at this point I do not see racing it. I expect it to be sailed hard and endure some damage. OK, so to restore it I would have to totally restore the hull shape. As a racer a DSII is not useable. As a former racer I want her to perform well.
Greenlake I like the info on battens. Thinking outside the box. What would be the effect of putting the batten on the outside? Performance wise? It would make it more durable for coastal sailing. I think the process you outlined would work great to restore the shape of the hull. The battens would stiffen and be sacrificial on beaching.

For Tx 200 you are building for endurance. So, first order of business is to deal with those cracks you found. And inspect your CB, because it looks like it must have grounded hard.

Outside stringers (like miniature bilge keels) would slow down the boat some, but in the Tx200 (assuming an "average" year) you are not fighting for power, but I understand from John, that this was definitely not the case on the last day this year. You would need to get them to be very parallel and very well faired or your losses will be that much larger. I see only limited benefits in grounding. The DS takes the brunt of any grounding on the forward half of the keel, where it has that V shape.

If your indentations are deep enough, then simply using a spacer material and adding a new, flat, layer of glass will give you the effect of a sandwich. The strength of a sandwich comes from having two layers of laminate separated by some distance. Relatively minor separation will have a noticeable effect. Fairing compound may be too expensive (and too heavy) as a separator, but you'd want something that you can attach to the deflected surface but that you can then sand flat. And it needs to be strong enough to act as a separator.

Variations of the theme include grinding off the gelcoat from the repair area (it's just dead weight) and/or adding one layer of biaxial cloth on the deflected hull first (to make up for any deficiencies of the "tired" laminate. Then continue turning the hollow into a sandwich.

A sandwich would be a 2-D reinforcement, where a stringer is really more like a linear beam. The problem is that the way your damage is oriented, a lengthwise reinforcement would be of limited utility. You need 2-D or crosswise stringers (and then you'd need to fit them on the inside - you definitely don't want to sail with crosswise ribs on the outside of your hull )

A more "rough and ready" repair would be to grind off some of the gel coat (at least the areas near the outside of the deflected area) then simply add 3-4 layers of laminate (about what the original hull would have had) on the outside, grind the edges smooth and fair (within reason). You might be left with remaining "suction cups" under your boat, but you would be sure that you have at least one layer of laminate with full integrity. Depending on how hollow things end up, it won't be as fast as it could be, but I assume it would be faster than "bilge keels."

The Tx200 crowd might advise you to just nail some plywood under there and paint it with hardware store house paint

But I'm sure you'll think of something better.

[Kleanbore]

I sold my DSII last year, and my hull was in great shape, but that didn't stop me from thinking about how I would approach major hull damage if it occurred. Sailing on Canyon Lake, TX there were plenty of opportunities to hit stumps when the lake levels dropped to historic lows.
I think I would go along with Greenlake on using a caul on the outside and patch the holes after the fact, but that still leaves the issue of how to insert a stringer from the outside. Before buying my DS I had a trashed up Hobie 16 with delaminated decks and some delamination in the side of one hull. Since the boat was trash (and I sold the trailer for more than I had in the boat) I decided to play around with fixing the issues. The Hobie 16 has fiberglass - foam - fiberglass sandwich construction which is strong and stiff until it delaminates. With nothing to lose, I used a thin blade in my angle grinder and cutout the deck just outside the textured areas. I carefully pealed back the decks where still attached to the foam core and placed them aside. I then removed the foam and cutout the inner glass layer, leaving an inch or so border all around. This gave me wide open access to the inside of the hull to repair the delamination. This access also allowed for stringers to reinforce the weak spot in front of the pylons. After the work was done inside, I laminated a layer of glass fabric on top of the old inner layer with an inch or so overlap all around to create a shoulder to reattach it with epoxy. I then laminated strips on the inside of the top decks to form a lip to attach the decks. Next step was building a new foam core with expanding polyurethane foam (marine grade) which was sanded down to the level of the deck. Epoxy the deck back on, grind the seam, laminate tape in the seam and refinish.
I think the same could be done on the cockpit floor of the DSII without all the foam issues.

[jeadstx]

Opening up the cockpit floor to do the repair, then making the cockpit deeper after the repair might make the DSII more comfortable to sit in for extended sailing.

John

[klb67]

I'll preface this by saying I don't know what I'm talking about with any degree of experience. I also can't really see how bad the damage is to your boat.

What would happen if you rested the boat mostly on the keel (possibly on the trailer with the bunks lowered), had some way to stabilize the boat, and began filing the bilge with water and let it sit for awhile with the bilge holding water? Would it help push the hull back out to where it belongs?

One minor data point - I got a new trailer for my 76 DS II this year. I swapped out the trailers this spring where it is dry moored. I raised the new trailer bunks as high as they would go, and lowered the center rollers as low as they would go. With the boat on the new trailer, most of the weight was still on the keel, and much less weight was on the hull on the trailer bunks. I had decided I needed longer bunk brackets to raise the bunks up another inch or so. The trailer was stable to sit, but I was afraid if I towed it, the boat would rock and damage the hull. I went back in a few weeks to take some measurements, and the hull had settled and was resting much more solidly on both bunks - the boat would not rock as it had before. There is no way for the center rollers to have dropped any farther, so the hull must have relaxed and settled on to the new, longer, bunks.

I careened my boat on its side for CB repair later this past summer after doing the trailer swap. There are no cracks or damage to the bottom of the hull, either in the bunk location, CB location, or elsewhere. I can see where the hull is slightly deflected where the bunks are, but it is very minor. I assume it was more so before I switched trailers and let it sit. I would also say that there is not too much weight on the keel, as it loads and unloads quite easily.

Good luck on your project.

[GreenLake]

Permanent deformation of a fiberglass hull is always a sign that warns of damage to the laminate. It's not enough to push the laminate back to its original shape. It will have lost strength. Even it it hasn't deformed much, but can be bent readily, that would be an indication that the matrix between resin and glass has loosened. To get back to the original strength (or better, so as to avoid repeat damage) takes a bit of extra work.

I like @Kleanbore's approach, except if any piece cut out of the hull is (nominally) a flat panel (or has a single, not a compound curve), I would not hesitate to re-create it on a table, rather than trying to salvage damaged laminate. With a nice lip, or with a properly scarfed join, or a combination, it should be possible to plug the cutout. It's also possible to go larger with the cut outs than you could with inspection ports. 8x8 square is already much larger than 8" round, but I see no reason why one couldn't cut an even larger hole.

The trailer bunks should extend further back than where they were (based on the marks on the hull in the pictures) and of course be much wider.Dropping the central rollers in the back so that they only support the bow for the first few feet of loading works well. (having a notched rear roller to center the bow works well). I retained a roller under the CB, up against the hull, so that the CB would not hang on the pin. I support the bow on the forward rollers. Others are using a keel-bunk. I can see how that provides even better support (although I think the keel is rather solid on the DS and while I've seen marks from when I had black rubber rollers, I've never seen cracks or soft spots where the keel has its deep V.

Can't wait to hear progress reports rolling in.

[K.C. Walker]

I must say, I love the brainstorming that goes on, on this forum. When I put a core in the bilge of my DS1 I did a lot of brainstorming here and got a lot of help.

Having a solid and stiff hull makes the boat feel completely different from one that is soft. I would guess that it is very likely that the bottom of this boat is very soft. Those are some pretty huge dents. I'd start by evaluating whether the bottom is, indeed, soft by checking how easy it is to deflect the bottom. If you take your closed fist and bang on the bottom and it bounces rather than feel solid, it's pretty soft. If it feels rock hard, then I would say fairing might be the easier solution. This is when you would want to decide on your commitment to this boat.

I always considered the DS 2 to be almost impossible to make this kind of repair. Obviously, I was not thinking correctly. I think the idea of cutting the cockpit sole out to have complete access would make a restoration very possible. Also, the idea of lowering the cockpit sole makes very good sense. Sure, it would be a fair amount of work. But, if one were to cut the sole out, laminate a structural foam (Core-Cell) core to the inside of the bilge and cover that with biaxial cloth at the same time extending the seat tank's and the bulkhead to integrate with this cockpit sole, the boat should stiffen up like crazy! Of course, it would no longer be self bailing, if that matters.

If the hull is actually stiff enough, or relatively stiff, or maybe even somewhat soft, filling the dents with structural foam might do the trick. It would be lighter than using fairing compound and most likely would end up being less expensive. It's pretty easy to sand with a coarse grit. So you could laminate strips in the dent sand them a little under fair, laminate some glass cloth or biaxial over that and you'd have made an incredibly stiff portion of the hull. It would probably act like a stringer.

Interesting thoughts, however I would think about how much commitment you want to make to this boat. Good boats can be found for relatively little money. This kind of work can easily lead down a rabbit hole.

[Kleanbore]

Greenlake made a great point about weakening of the laminate from deformation. Working from both sides, I think I would cut a longitudinal slot in the bottom of the deformation to make it much easier to pull out to the caul. Ribs could be glued on the inside of the hull at the same time. Grind a taper on either side of the slot and laminate graduated strips on the outside.
I see your other post about the centerboard trunk issue. Working from inside would allow for a nice opportunity to brace the centerboard trunk. Ribs extending from the stringer up the trunk should make a really stiff hull.
Maybe there's hope for a faster DSII ?

[GreenLake]

If not a faster hull then one that has less to fear from grounding in the shallow waters of the Tx200.

There are a lot of useful ideas on the table, so I will just add one small comment. If you add anything on the inside of the hull, make sure that you do not trap any water in the bilge. That's why I suggested hollow stringers. If you connect them to the CB trunk (not a bad idea in itself) add some holes so water can run along the lowest point of the bilge to the drains.

I did not know that structural foam core sands easily enough to make a taper possible. That sounds like a nice way fill deeper dents then.

Swashbuckley says that he is preparing the boat for the Tx200. The group that sails that event is very eclectic -- just read their reports or check their facebook banter. On the one hand, they are serious about survival, self-reliance, preparedness, redundancy and all that stuff, on the other hand, there's a streak of "lets see what's the most minimalistic approach" to get the job done, as in avoiding the fancy touches, or going for very minimalist boats.

While they intend for their craft to survive a grueling week and 200 miles, and to get them safely through the adventure, they don't necessarily intend for their craft to survive beyond the finish line. There are tales of boats being burned upon arrival (wooden ones, to be fair).

Where on that curve Swashbuckley places himself will define his approach. I think it could well be different from what most of us would choose for a regular "restoration" where the aim is to take a few decades off an old boat and get one that's "like new" or even "better than new" and enjoy it for many years. I'm curious what his decisions will be and how he approaches this issue as well as the remainder of the task (getting foils and rigging to a functional state, preparing a spare tiller/rudder and all the other preparations).

I'm looking forward to many more occasions for future brainstorming with him.