Has anyone separated hull from deck on a DS II?

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Has anyone separated hull from deck on a DS II?

Postby Felix Graham-Jones » Fri Jun 04, 2021 9:15 pm

Serious injury to my beloved but tired old (1972) o'Day built DSII has me contemplating the feasibility of separating hull from deck.
The injury is a slash just forward of the centerboard case that is a longitudinal slash about 6inch long but it has a ragged tear crosswise at the forward end.
So it would be a tricky repair anyway because, being a DS II, I can only get at one side of the repair.
But the slash reveals gobs of very sick soggy looking styrofoam trying to get out.
Many years ago I did a whole winter's project digging out and repairing gel coat blisters, fairing and then barrier coating the boat's bottom. But this spring I noticed that new blisters had formed. My guess is that soggy foam runs all the way under the cockpit floor of my boat and I'm wondering if anyone has successfully separated hull and cockpit moldings. I could then, not only easily get at and repair the hull slash, but also remove and dry out the whole interhull space and replace the styrofoam with closed cell noodles.
If it's doable, it would be a great opportunity to i) improve the centreboard up and down hauls so they don"t leak into the inter-hull space AND ii) stiffen the hull so it doesn't beercan (flex) so easily. Anyone got any thoughts on those additional projects?
Fair winds...
Felix
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Re: Has anyone separated hull from deck on a DS II?

Postby GreenLake » Sat Jun 05, 2021 3:35 am

Do I understand correctly that your damage is underneath the cuddy floor? (Forward of the CB)

In that case, the solution would be to cut a generous opening in the cuddy floor (large rectangle) leaving just enough along all sides to comfortably tab the cutout back in place when done. (Closing the opening would mean glueing some strips of pre-laminated epoxy on all sides under the bits you've left over so that you get a bit of a shallow L shape. With the large opening you can easily clamp these strips. Then lay the cutout on top and glue in place. Finally fill the remaining groove, perhaps even with some high strength filler.)

If the damage is so far forward that it extends under the flotation tank at the front of the cuddy, cut a large circular hole centered in the bulkhead (sized so it can later be closed with the largest screw-in deck plate that you can source).

This would allow you to access the repair from the inside and remove any soggy foam (my suspicion is that the foam is in the tank portion only - that would be typical).

In case you are wondering, it is totally possible to make a repair from the outside only: you would lay up a "backing plate" that is a bit wider/longer than the gash, but thin enough to be flexible. You enlarge the gash by removing all torn laminate, and bevel the edges. The you reach in and rough up the inside. You insert your backing plate and glue it in place with epoxy. Slightly thickened, or use one per-formulated as a glue, like Gel-Magic from SystemThree. You can drill some holes and use screws, or even pop rivets to hold the backing plate tightly against the inside of the hull, so it conforms and helps the hull to assume a fair shape across the gash. When the glue has set, drill out the rivet (take out the screws, if you remembered to wax them beforehand).

Now you have a low spot in an otherwise fair hull: fill with layers laminate going to smaller sizes, not larger as you add layers in your stack. Fair and finish.

Even if you can access the inside, you may want to use this backing plate method, mainly to make sure the hull isn't distorted. Using fasteners to hold the backing plate is likely to give better results than pushing it from the inside (it's tough to make it lie flat -- as I experienced with a repair that had inside access). However, getting the backing plate in place and even adding the temporary fasteners may be just a bit easier from the inside. Working from the outside, you may need a string or wire to the middle of your plate so you can pull it against the hull while working to fasten it.

You might also want to read this post: "ten steps to adding a patch"
~ green ~ lake ~ ~
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Re: Has anyone separated hull from deck on a DS II?

Postby GreenLake » Sat Jun 05, 2021 3:41 am

PS: if you couldn't tell from the preceding, my take is that to completely deconstruct your boat sounds like a bit of overkill. Also, blisters are caused by the laminate pulling water by osmosis from the side the blister appears on. Unless your blisters are on the inside of the hull, the water in question would not be from the soggy foam. (Most people remove the soggy foam by cutting a few well-placed holes that can be closed with screw in deck plates).

Here's a picture somebody did of their removal of foam from the forward tank of a DSII:
1221
(click to enlarge)
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Re: Has anyone separated hull from deck on a DS II?

Postby Felix Graham-Jones » Sat Jun 12, 2021 1:30 pm

Green Lake,
Thank you for TWO cogent and very helpful replies.
The poor injured boat is not at my home so making sense of your proposal took a couple of days.
I am still considering my options but you're very right - accessing the injury through the cuddy floor IS the way to go.
One thing noted during this sorry episode is that the drain plug which SHOULD drain everything out of the interhull space, which is dead on the transom centreline just below the lower rudder gudgeon, does NOT in fact allow water to leave that space. In order to get the water out from between the moldings I had to drill holes into the flotation tanks under the seats. I plan to enlarge those holes and put inspection ports there - and that will let me pull out a bunch of the soggy foam, but how do I get at the space between the cockpit sole and the hull?
If i was to cut ANOTHER pair of inspection ports through the cockpit sole somewhere a little aft of the back of the centre board case (I already have one pair through the sole at the front of the cockpit) I could then really clear out the interhiull space. Would it then make sense to think about pouring in/squirting in some of that closed cell expanding insulation foam? This would then provide permanent (irretrievable) flotation AND probably stiffen the hull a bunch.
Anyone have any thoughts or comments?
Thanks
Fair winds...
Felix
Felix Graham-Jones
 
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Location: NW CT

Re: Has anyone separated hull from deck on a DS II?

Postby Alan » Sat Jun 12, 2021 4:48 pm

There might not actually be much foam in the space between the cockpit sole and the hull. All I found in the bilge of my 1980 DSII (that's the one in the photo above) was a few random pieces. The bow tank was packed full, as shown in the photo, and since the bow tank is open to the bilge, some of the pieces may have worked their way down there.

I agree with the idea of cutting an access port in the cuddy floor to make the repair. Something to watch out for: I don't know if the 1972 boats had this, but in my 1980 there's a built-in fiberglass flotation tank in the bilge, about halfway between the bow and the cuddy bulkhead (forward of the mast). It runs crosswise to the bilge and looks like it's filled with foam. If you can see through the gash into the bilge, it would be worth looking to make sure the tank won't obstruct your repair access.

Before you go to all of the trouble of making new access ports in the cockpit sole, you might try lowering a small camera into the two access ports aft of the cuddy bulkhead, and taking a lot of photos of the space between the cockpit sole and the hull. I did that, and I didn't find any foam.

The bilge drain plug was located in the center of the transom on early DSIIs. The most likely reason it didn't drain on your boat is that the hull and cockpit moldings are extremely close to each other at that point, and any leftover detritus from assembly, or flotsam drifting around in the bilge, would clog it. On later DSIIs like mine, the bilge drain plug was relocated about a foot to starboard, where it opens into the cavity formed by the starboard seat. (The cockpit drain plug remained in the center of the transom.)

If it were me, I'd stuff the bow tank and underseat cavities with pool noodles. You might also want to stuff the bilge underneath the cuddy with pool noodles.

Hope this helps. Good luck.
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Re: Has anyone separated hull from deck on a DS II?

Postby GreenLake » Sat Jun 12, 2021 4:59 pm

Alan, that extra bit you found below the cuddy floor - do you really think it's a "tank" or is it a foam-filled stringer or other reinforcement? Can you share, or re-share any pictures?
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Re: Has anyone separated hull from deck on a DS II?

Postby Alan » Sun Jun 13, 2021 2:19 pm

GL: There are two stringers on the underside of the cuddy floor, spanning the width of the hull, but they're firmly attached to the cuddy floor and are only about two inches deep in the fore-and-aft direction. The tank is maybe 8-10 inches deep, fore-and-aft, and not attached to the cuddy floor - there's a small gap between the top of the tank and the floor. It's more like a bowl.

I posted photos on a thread a while back, probably in 2017 or 2018, but I can't find the thread (I've tried using an outside search engine and the site search engine, as well as scrolling through my posts. Maybe I just missed it.) You and I talked about it at the time and you asked for clarification, which I hope I provided. I'll look some more after I've made some progress on today's honey-do list. :lol:

Felix: I forgot to mention the stringers - they're structural members, so you don't want to cut them if you can help it. You can see the aft one by looking into the bilge through the existing inspection ports aft of the cuddy bulkhead, using a bicycle mirror or similar and a flashlight.
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Re: Has anyone separated hull from deck on a DS II?

Postby GreenLake » Sun Jun 13, 2021 2:47 pm

Stringers attached to the cuddy floor are there the support that floor and not the hull. That would be my guess. If that's a correct guess, and you cut through them, you'll have to figure out something equivalent to support the cuddy floor, but won't impact the boat otherwise. It's a complication best avoided, if your aim is simply to create an access in the floor.
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Re: Has anyone separated hull from deck on a DS II?

Postby GreenLake » Sun Jun 13, 2021 3:24 pm

I found this image in one of your posts
Image
where you write that the dirty white pieces are foam and the stringers are clearly visible.
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Re: Has anyone separated hull from deck on a DS II?

Postby Alan » Sun Jun 13, 2021 3:38 pm

Aha! Thanks, GL. That one shows the stringers, the compression post, and looking forward, a vertical wall. That's the aft wall of the tank. The fiberglass stuff in the right of the photo is the leading edge of the centerboard trunk.

There are some other photos somewhere identifying the tank specifically, including from the front. I got the front ones by dangling a camera into the hatch I installed in the forward cuddy bulkhead.

By the way, I think those foam pieces must have been installed before the cockpit molding was attached to the hull. They were too long to have been installed through the factory access ports or to have fallen from the bow tank.
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Re: Has anyone separated hull from deck on a DS II?

Postby Alan » Sun Jun 13, 2021 4:30 pm

And following up: I found the post I was thinking of, here:

viewtopic.php?f=2&t=5159&p=28261&hilit=jeadstx#p28261

About two-thirds of the way through page 2 of the post, there are photos of the tank, as well as a photo I borrowed from John Alesch's gallery.
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