The album of Ariel #422

[mrgnstrn]

Kurt

Your flotation project got me thinking...

As I recall, you are planning on putting in just enough extra flotation to basically float the boat at it's gunwales. Basically, this is mostly a submerged body. So you may want to consider a few things:

VCG, VCB: Vertical center of bouyancy and V.C. of gavity. You will want to make sure that the VCB is above the VCG, otherwise your boat will be more stable upside down than right side up. (note, this is necessary only because you are now a submerged body, like a submarine. Once you are not a submerged body, you can rely on form stability to help keep you upright)

LCG, LCB: Longitudinal center of bouyancy and L.C. of gavity. This one would be a bigger concern to me. If these two don't line up on top of each other, your boat will float with the bow skyward and stern 26' below the surface. (or vice versa). How are you going to recover from that, even after you fix the hole? It's not like you can bail out the stern....it's totally submerged.

Lateral CG and CB may also be a concern, but if you put approximately equal flotation on port as starboard, you might be able to deem yourself OK.


Also, you might want to think through the repair and recovery process. OK, you have hit a submerged container, put a 10" gash in the leading edge of the keel, quickly taken on enough water to sink the boat, but the flotation has kept the boat from becoming a coral reef project.
Now what?
How do I repair the problem? Do I need to careen the boat way over to reach the hole to repair/patch it? Can I do it all underwater? After I have repaired the hull, how do I get the water out? Are all the gunwales above the water, can I bail, can I shut the cockpit scuppers to keep from filling back up the cockpit? is water draining into the cabin, cockpit lockers from the cockpit? if the lockers are sealed, how do I drain them?

What this led me to believe is that you need to have some temporary flotation bags to enhance the flotation for recovery.

Don't get me wrong, your passive flotation solution is very elegant. Always there, don't have to worry about it not working, no moving parts to fail at the wrong time. And these inflatable bags may be unsuitable for permantent installation and use in an emergency.

But after things have calmed down, you may need to pull these bags out to lift up the bow to fix the hole, or stern to fix a rudder problem, or to lift the gunwales well clear of the waterline for bailing. And if you are crafty, you could make them blow up with those handy sized CO2 cartridges they use on lifevests. Or the similar sized cartridges they use for air-guns. And you can store a lot of them for a long time, until needed. That way if you need to inflate and deflate it a couple of times for all the necessary recovery operations, you can.

food for thought.

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oh, and just thought about this.....Don't you also own "Nemisis" up on Maryland? Why not trial sink that boat instead of you beloved Katie Marie......?
Then give the hull to Tim Lackey and have him do something amazing out of it....Like make it fly or something!
(clarification, Lackey is a true genius and artist with a boat hull. Nothing else implied herein)
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