FWIW for those who race a Hobie 18 or similar cat, I just removed the foam flotation in the port hull and thought I would pass along some observations.
The foam was waterlogged (hull is "redline" 84 Coleman).
Am estimating the weight of the two flotation pieces was 25 lbs for one hull.
Blue gloves with work glove over...mask in case...I discarded after half hour. Acquire some CPES or Git-Rot to seal balsa core.
Tedious task:
I carefully cut out the deck for a 4" curved Viking inspection (access) port...
The aft hull deck is balsa sandwich.
The cutout has to be a 1/16 or 1mm wider than the insert base, due to second lip on the base. Draw line and cut so line is just visible. I used Sears vibrating style cutter...for hole.
Anyway, I put large recycle bag on floor for plastic and had vacuum nearby. Beads cling most everything.
I began using a Sears vibrating cutter with wide blade, but quickly switched to a hacksaw blade and glove. Much faster and easier to wield inside hull.
The foam block is made up of two separate pieces, shaped to inverted "V" and joined to form rectangle.
Slide one piece aft and simply begin sawing. That is very easy...you will quickly figure it out...small chunks, to pass through hole. I began with the "V" section side of one block and worked down.
Each block takes about an hour.
Vacuum inside of hull.
I then roughly angled the exposed edges...and coated with a product called "CPES," which soaks into the balsa core...epoxy. I then coated the same edges with epoxy. You could use Git-rot, etc or even the West Epoxy glue, I believe.
Idea is prevention - to seal the balsa from water vapor for obvious reasons.
Inserted some 10 long, solid pool noodles (about $3. USD each, to approx 1.5 - 2 cu ft volume) replaces the flotation, although some suggest no flotation is needed???
One could recycle sealed juice or water jugs, etc.
Like I implied, job is bollocks...
But had to be done. Already fixed a split bottom just forward of dagger trunk (glass/epoxy) and old beat hull is as good as new etc.
Edited by BobBill on Sep 01, 2013 - 06:03 AM.
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Hobie (18) Flotation - Removal
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Posted: Sep 01, 2013 - 05:57 AM
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Posted: Sep 01, 2013 - 06:45 PM
Does the foam really do anything though?
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Rob Jones
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Posted: Sep 02, 2013 - 05:22 AM
if i filled my nacra 5.2 with water
it would sink like a rock
the foam blocks were cheap insurance for the hobie lifestylers -
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Posted: Sep 02, 2013 - 12:27 PM
Some suggest the hulls may float without the foam, but why take the chance?
Erice, I am fairly certain my Hobie would sink as well and why I will add the pool noodles.
The idea was to remove the weighty foam. The boat is perceptibly lighter...10 noodles or so will not be noticed.
Just a heads-up is all.
BTW, I am looking for one lower Hobie 18 rudder casting, new or old style...decent. PM or leave note here?
I may take a day or so to get back.
Edited by BobBill on Sep 02, 2013 - 12:31 PM.
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Posted: Sep 02, 2013 - 01:11 PM
I like the pool noodle idea because you can pull them out easily. If you breach the hulls badly enough to put yourself
in a sinking situation you probably did it over a shoal, groin or jetty. In that case you are probably in shallow water.
To sink her in deep water you would have had to forgotten the plugs and not noticed for a while. A catastrophic collision or hull failure could put you in a sinking situation if you totaled both hulls. I'd like to hear from somebody who has flat sunk a cat or seen it happen first hand. I'm not saying foam floatation is a bad idea but it does adsorb water and increase weight. GH
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Posted: Sep 02, 2013 - 01:14 PM
It also deteriorates and crumbles...if cat is old enough, might be alternative...particularly if you race the boat!
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Posted: Sep 03, 2013 - 11:32 AM
BTDT
2 years ago I flooded a Hobie 18 port hull (1986), on Galveston Bay. Discovered the problem when the boat tried to pichpole and didn't immediately sort itself back out when we dumped both sails.
The flooding was caused by cracks opening up at the outboard front and rear crossbar joints and the inboard front crossbar joint of the port hull. I had the foam blocks in the hulls.
We put the crew on the starboard hull (leeward) and were on a port tack, the port hull was awash most of the 7 miles back to the beach.
When we got to the beach, the boat ran aground in about 6" of water. We opened the inspection port, and found that there was abour 2" to 3" of the hull NOT filled with water. I pulled the drain plug to let the water level equalize, then floated the boat onto the wheels to pull her out. Not fun.
I think that without the reserve bouyancy of the foam we would have been in deeper doo doo, and had to swim some...
YMMV
E.T.A. - The head pressure (hydrostatic) of the water in the hull blew the drain plug out of the through hull fitting when I unscrewed it.
http://www.thebeachcats.c…ctures/?g2_itemId=103830
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Posted: Sep 03, 2013 - 02:10 PM
Presto, makes sense to me. Nothing left to chance...pool noodles for me too.
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Posted: Sep 06, 2013 - 10:43 AM
I must add, do not forget to cover fastener holes in sandwich areas with cpes also. You never know, caulking or not, best keep all moisture from wood core.
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Posted: Sep 07, 2013 - 09:51 PM
Just so you know. There is no wood in a Hobie 18. It's foam core, not balsa core.
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Posted: Sep 08, 2013 - 04:26 AM
I did not know that...thanks. I know crappola about Hobie construction. Am anal.
I figured balsa in forward and stern sensible. (It is not present midships.)
When I cut into it to make the ports, it looked like balsa sandwich and acted like it, so I figured it was...red line and all.
Very good and thanks again.
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Posted: Sep 08, 2013 - 07:33 AM
FWIW.
I thought I would add a comment regarding weight removed...
With the soggy flotation in the boat, the balance point was just aft or center of the dagger board slot...
Removed, the boat is significantly lighter and the balance point shifted just aft of the forward crossbeam.
Am guessing the weight after removal is how the boat came out the door...
Not sure about pool noodles positioning, but plan to tie every two together near ends, so they are double-length but connected, for ease of adding and to position inside hull.
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Posted: Jul 09, 2014 - 11:15 PM
FWIW, I removed 4 pool noodles, as I think 6 are more than enough to float a full hull. Just a guess.
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Posted: Jul 10, 2014 - 06:46 AM
this foam always looked inadequate for the job but when my friend stuffed bottom and ripped his bow off the boat, he was able to "float" the hull and sail home
pool noodles are not good quality foam and will water log much faster than the foam you removed
the foam blocks in my boat are secured to the boat on a stringer - water noodles will spill out in the event of a catastrophic failure (what they are there for) - so secure them somehow -
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Posted: Jul 10, 2014 - 06:47 AM
marine grade silicone is better than window/tub caulking -
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Posted: Jul 10, 2014 - 07:52 AM
MN3, Am always willing to learn. Thanks.
As to the pool noodles:
Been using pool noodles for decade or so, good 5-inch solid core noodles.
They are spendy (10 $coots per) and do not absorb water at all.
The buoyancy per square inch surpassed that of closed cell foam, all closed cell foam, as I recall at the time, and that may have changed over the years. I have not checked, no need to.
Moreover, there is no good way to r&r (remove/replace) foam blocks when soggy, obviously.
I have foam in a H-16 hull I am using as an outrigger, and did not remove it as it was dry, but then that hull has been out of the water since 2009.
If the hull picks up some water and the foam becomes sogged, it will be removed and replaced with 4 or 6 easily procured and installed pool noodles-NOT from Wally-world etc.
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Posted: Jul 10, 2014 - 09:32 AM
sounds much better than the $2 versions i see everywhere (not solid)
I use the yellow ones when we go camping - they are great at making invisible tent guy lines visible (and saving someone from a face plant into a rock or fire pit).
those cheap ones get soggy
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Posted: Jul 10, 2014 - 09:39 AM
Aye-Aye! Pesky guy-lines...neat idea, though I end up crawling around eventually.
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Posted: Jul 10, 2014 - 04:42 PM
Somewhere I read that the total foam volume in the 18 was about 1.5 cubic feet per hull. A 5" solid pool noodle that is 55" long has a volume of about 0.625 cubic feet. 3 per hull should do it.
ETA: I did use Excel, and I am an engineer.
Edited by presto13031 on Jul 10, 2014 - 05:44 PM.
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Jeff
Houston TX
1986 Hobie 18 Sail# 13031
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Posted: Jul 11, 2014 - 05:58 AM
Jeff...freaking excellent and useful info, much appreciated. Great to compare for other boats.
Three it is.
I guess the 6 on each side in my 11 foot Kite are overkill...but great storage place, however.
Edited by BobBill on Jul 11, 2014 - 05:59 AM.
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