# On floatation tanks and their access **URL:** \ **Category:** Builder's Forum\ **Created:** [June 22, 2020, 5:30pm UTC](https://forum.clcboats.com/t/on-floatation-tanks-and-their-access/47787 "2020-06-22T17:30:27Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![William\_Hackworth](https://avatars.discourse-cdn.com/v4/letter/w/eb8c5e/32.png) [@William\_Hackworth](https://forum.clcboats.com/u/William_Hackworth)\ **Post date:** [June 22, 2020, 5:30pm UTC](https://forum.clcboats.com/t/on-floatation-tanks-and-their-access/47787/1 "2020-06-22T17:30:27Z")
I took a break from working on the Jimmy Skiff II today and took my Skerry sailing, promptly capsizing for the first time. The fore and aft flotation tanks did their jobs and kept the daggerboard opening about 2” above water, allowing me to bail out.  It was calm out; in choppy conditions I don’t think bailing would have worked.  I think I will add a float bag below the middle seat before my next outing. On returning to shore, I found that both floatation tanks had a gallon or two of water in them.  The tanks each have the standard 4” Seadog deck plates bedded in a generous amount of silicone, and were tightly closed.  The fillets are airtight so I can only presume that the water leaked through the deck plates.  Had I needed more time to bail,  I expect the tanks would have eventually filled with water.   So anyway, this got me wondering about access to the tanks on the Jimmy Skiff II.  There are port and starboard tanks (filled with construction foam) under the seats, and a large empty bow tank.  I had planned to use the same deck plates for the side tanks, and was considering a rectangular 8x12” hatch for the bow tank to allow for easy access and storage.  The rectangular hatch would be even less watertight than the deck plates.  After my capsize today I am definitely reconsidering.  It seems like maybe it would be best to leave the tanks fully sealed. The lovely Skiff reviewed in Small Boats Monthly doesn’t seem to have any access plates at all.  The model on CLC’s site seems to have 4” deck plates on the side tanks.  The bow tank appears to have had a sea-lect watertight kayak hatch added later after some of the initial photos were taken. Has anyone who left their floatation tanks fully sealed actually experienced issues with air pressure or condensation?  Alternatively, can anyone recommend a truly airtight deck plate? Many thanks!   ---
**Author:** ![David\_Poole](https://avatars.discourse-cdn.com/v4/letter/d/82dd89/32.png) [@David\_Poole](https://forum.clcboats.com/u/David_Poole)\ **Post date:** [June 23, 2020, 4:41pm UTC](https://forum.clcboats.com/t/on-floatation-tanks-and-their-access/47787/2 "2020-06-23T16:41:18Z")
Yes and no. I had leaks at the base of the dagger board well. Rather good leaks, but it lasted quite a while in the water before noticed. Don’t assume all your joints are good. I .am considering adding hatches so I can dry it out. The drains didn’t get it all and it leaked on the shop floor when we turned it over. ---
**Author:** ![Laszlo\_Morocz](https://avatars.discourse-cdn.com/v4/letter/l/c68b51/32.png) [@Laszlo\_Morocz](https://forum.clcboats.com/u/Laszlo_Morocz)\ **Post date:** [June 23, 2020, 9:33pm UTC](https://forum.clcboats.com/t/on-floatation-tanks-and-their-access/47787/3 "2020-06-23T21:33:28Z")
I had a hermetically sealed air tank in my schooner. When I removed the cleat that was screwed into it during revarnishing, there was a loud hiss as the tank pressure equalized with ambient pressure through the screw hole. That's about the only thing I noticed. Laszlo   ---
**Author:** ![David\_Poole](https://avatars.discourse-cdn.com/v4/letter/d/82dd89/32.png) [@David\_Poole](https://forum.clcboats.com/u/David_Poole)\ **Post date:** [June 25, 2020, 4:32pm UTC](https://forum.clcboats.com/t/on-floatation-tanks-and-their-access/47787/4 "2020-06-25T16:32:45Z")
   Look for deck plates with a flange and o-ring seal under the flange. Requires the thing to be tightly closed though.