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bouyancy tank contents

PostPosted: Wed May 28, 2003 12:27 pm
by Roger
I was wanting to cut into the bouyancy tanks under the seats to install, spinnaker sheet block backing plates. I was recently into the forward bulkhead to replace the boweye on the weekend. I still have abraded knuckles from picking out a foam tunnel to the back of the boweye. I am wondering if the side bouyancy is also foam filled or if they are air tight and hollow?

PostPosted: Thu May 29, 2003 10:25 pm
by Guest
Roger, I think the DS I had air tanks under the seats, there may be foam in there, but I've heard of owners stuffing "waternoodles" into the seat tanks for added flotation, so that would lead me to conclude that there is no foam. Are you mounting the spinnaker blocks on the seats? You should be able to get at the underside of the deck without cutting into the seats.

Rod Johnson, SUNBIRD (

PostPosted: Thu May 29, 2003 10:39 pm
by Bob Hunkins
With the older boats it is not uncommon for the styrofoam flotation to become waterlogged. It's a god idea to remove and replace waterlogged foam with new floation. The waternoodles are an excellent choice. It's important to replace the flotation. First, for safety reasons and second, if you race the boat class rules require it.

PostPosted: Fri May 30, 2003 7:43 pm
by Roger
Rod, you said... "Are you mounting the spinnaker blocks on the seats? You should be able to get at the underside of the deck without cutting into the seats."

I am mounting the Spinnaker blocks ~12" in from the transom and about 3" in from the gunwale at the back outside the seatbacks (that would make it the deck), but my question is how do I get to the backing plate... I thought I would have to go through a (not yet made) access hole under the seat or at the seat back to access under the deck. I have a DS II. How do I access it otherwise?

PostPosted: Sun Jun 01, 2003 7:52 am
by Guest
Roger, your question sounded like you had a DS I. On the DS II you will have to cut a hole and use an inspection port to reseal it. In answer to your earlier question about flotation in that area, as far as I know there is nothing but air up in that region. From what I've encountered on my boat, all the flotation is in the bow and under the seats. I ran a PVC pipe up under the deck from the inside of the cuddy to the stern to run wires for my NavLights through, and encountered no foam. Actually, the DS II would probably float very well if she had a hole in the hull, even without flotation. Mine had a leak when I bought her, and with the flotation and an intact deck/cockpit and inner liner in the cuddy, she barely sank 4" even with a completely full bilge (I opened one of the cockpit inspection/bailing ports and water flowed out of the bilge into the cockpit.
I really like my DS II, but have to say that there is far too much "wasted" and inaccessible space due to the molded-in cockpit. However, a DS I does not have a lockable cuddy or a "self-bailing" cockpit, so I guess it is a fair trade-off for me.

Rod Johnson, "SUNBIRD" (

PostPosted: Sun Jun 01, 2003 10:54 am
by Roger
Yes, my apologies if I mislead you into thinking that I was talking about a DS I. I do have a DS II, and was looking at the area where I might install the spinnaker blocks again yesterday. If I went fairly close to the gunwale, I could through bolt it, but I would rather put an inspection port in the seat back, and be able to access the aft cleats, and also the yet to be installed spinnaker sheet blocks.

You said you ran a pvc tube from the cuddy to near the transom area for your nav light wires. Did you run the tube behind the seat backs, or under the seat? Next question... How well does pvc adhere to epoxy? The reason I ask, is that when I was tightening the pivot bolt through the cockpit inspection ports (thanks to your information and pictures last fall), I noticed that the starboard stringer directly below the inspection port is rotten where a side to side drain hole passes through the stringer. I was planning to dry the area out, top it with a half round of pvc pipe and cover it with epoxy and cloth, keeping the side to side drain open. I had also thought about laminating in a chunk of hockey stick about 20 inches long.

PostPosted: Wed Jun 04, 2003 11:07 pm
by Guest
Roger, the pipe runs behind the seat back (cockpit coaming) it is basically just loose in the hole in the cuddy bulkhead (slightly larger than pipe O.D.) and is held by a screw at the aft end. There is no epoxy involved, only PVC Pipe cement at the joint in the pipe due to needing to cut the pipe in 2 pieces because the cuddy is not as long fore & aft as the cockpit.
I seem to recall that your DS II is older than mine, but all the stringers that reinforce the hull and deck on my DS II are fiberglass layed over foam (and kind of soft foam at that!). This is OK, the fiberglass is what actually forms a beam to stiffen the area. You can use PVC pipe for stringers, glassed over using Epoxy resin, just clean the pipe with a de-waxer and sand it a bit to add "teeth". I wouldn't trust using epoxy to "glue" the pipe halves to the hull, but if you used glass cloth to laminate the pipes to the surface it should hold. I would use the same method if you were to use the hockey stick wood.

Rod Johnson, SUNBIRD (

PostPosted: Thu Jun 05, 2003 8:19 am
by Roger
My DS II is a 1974 model. Foam eh! Well that makes me feel a bit better. I thought I had some rot in there that I might need to take care of. I'll have another look at it to make sure it is indeed foam, I might even be able to cut away some of the disintegrating stuff and add in some spray foam insulation, then cover with fg cloth as you indicate. It would save me laminating an extra beam if it is not needed. Structurally, all the the foam seems to be doing, if used this way in the original manufacture, is to create a form for the fg cloth beam, which itself is the structural member, not the foam. This boat never ceases to amaze me in design arcitecture.