Buoyancy question

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Buoyancy question

Postby SMHolmans on Tue Nov 19, 2019 2:44 pm

Has anybody considered using buoyancy bags rather than foam blocks in the bow and stern compartments? It seems to me that it might be easier and provide better access.
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Re: Buoyancy question

Postby Mflyer65 on Tue Nov 19, 2019 10:03 pm

Interesting idea. Would you then leave all flotation tank areas open to hold the bags? If they leaked then you would need access to replace them or otherwise patch I suppose. Can you get bag sizes that would fit the spaces?
This would certainly be more expensive than the foam approach but I like the neatness of it.
Mike
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Re: Buoyancy question

Postby SMHolmans on Wed Nov 20, 2019 1:54 pm

My main motivation for asking this question is to avoid making lazarette lockers in the stern. I have discovered that buoyancy bags are available from Crewsaver (here in the UK, anyway) in a range of sizes, so I can secure one with straps underneath the cockpit sole. That way I don't lose any storage space in the stern and I can remove the buoyancy for cleaning etc.

I am going to stick with foam blocks in the bow, as specified in the manual.
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Re: Buoyancy question

Postby Mflyer65 on Wed Nov 20, 2019 9:56 pm

I like it Steve. Maybe a few pictures to show it off if you do this? I am rethinking my own build for the stern buoyancy now.
Mike
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Re: Buoyancy question

Postby SMHolmans on Thu Nov 21, 2019 7:21 am

Yes Mike, I will post pics when I get to that point.

Here is a link to Crewsaver buoyancy bags … https://www.force4.co.uk/crewsaver-buoyancy-bags-m.html
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Re: Buoyancy question

Postby riverron on Fri Nov 22, 2019 8:37 am

I am past that point, but I do like the buoyancy bags in the lazarette area. It would be easy to replace. As I recall there is not much flotation and I have wondered how to remove any water that would get in there, since the low part is below the flotation. With the bag, you could deflate and remove in theory. Also something to keep in mind, you will loose a lot of good storage area if not building the lazarettes. You can seal that whole area off like some other builders did.
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Re: Buoyancy question

Postby SMHolmans on Fri Nov 22, 2019 3:08 pm

I'm getting a better idea about what to do, thanks to Ron and Mike.

If the compartment containing the buoyancy is completely sealed there is no way to dry it out in the event of water getting in, by damage to the hull for example … so removable buoyancy (i.e. a bag or bags) would be a good idea. However, as Ron points out using buoyancy bags on their own will use a lot of otherwise very useful storage space. So what I'm now thinking about is buoyancy bag(s) and a removable lid/shelf/grill of some kind. Then again, if I go down that route I might as well use ordinary foam blocks.

I will ponder further … never any shortage of challenges with PocketShip!
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Re: Buoyancy question

Postby mark48 on Wed Nov 27, 2019 3:57 pm

Hi,

Whatever you do, remember that a deep lazarette locker is an ideal space to store an anchor, and that anything big or metal (e.g., an anchor) might damage a flotation bag unless the bag is in a protected space. I extended my foam flotation blocks laterally and sealed the entire stern flotation area under plywood / FG / epoxy. Here's hoping I never have water penetrating that compartment - for several reasons. A consequence of my expanded stern flotation though is difficulty storing an anchor close at hand. I'm still working on that one.

All the best,
Mark
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Re: Buoyancy question

Postby SMHolmans on Wed Nov 27, 2019 5:06 pm

Thanks Mark. A very good point about anchor stowage. I'm still pondering ...
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Re: Buoyancy question

Postby Bflat on Mon Dec 02, 2019 1:54 pm

I keep lots of bouyant objects in my lazarettes, like extra life jackets and 4 fenders. The fenders are especially suited to this role since when they're in use I'm tied up at a dock and when away from shore they're stowed as stern flotation. I figure that the bouyancy may as well serve dual purpose rather than just be foam taking up space. Besides, I'd rather not have to store fenders in the cabin as they're often wet and take up lots of space. Even a small cooler, half used plastic bottle of motor oil and small half empty plastic gas can adds bouyancy. I do keep a small extra anchor in there as well, however. My main anchor I secure on the foredeck, ready to go in a moment.
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