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Go Back   SailNet Community > Boat Builders Row > MacGregor > how much foam in a Mac or Venture 25?
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Thread: how much foam in a Mac or Venture 25? Reply to Thread
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Topic Review (Newest First)
01-17-2009 09:05 PM
whamo2 A few years ago, there was a photo of a guy in a Macgregor 25 who had hit a floating hazard in New York harbor, and holed his boat. He was able to motor back into his point of origin, with about 12 inches of freeboard, due to the built in flotation.

The original version of the Pearson Ensign (3000 lb displacement) had no flotation, and several people were drowned when caught by bad weather while racing in San Francisco harbor. Subsequently, all Ensigns sold had foam flotation built in. Other similar sized boats having flotation (Air tanks or sealed compartments) include the Soling and the J-22. A friend left the flotation compartment on his Soling open, and had to hire a crane to retrieve his boat after it capsized and sank.

My first sailboat was a wooden 16 footer with a fixed keel and a 19 foot wooden mast. It was very easy to capsize and sank like a rock, but sat upright after sinking. I was careful not to sail in deep water so I could retrieve it if I capsized. Since then, I have stuck with boats having flotation.
01-15-2009 04:31 AM
minhthn Well I would think the foams are there for a good purpose. It will definitely help the boat sink slower if anything and you know when your boat is leaking a lot faster because the foam take up the space.
11-03-2008 05:11 PM
N0NJY
Quote:
Originally Posted by malcolmwill View Post
Gasoline inside my Venture? I think not!
WHAT!?!?!?!?

no puttputt motor like mine? (9 hp )
11-03-2008 05:01 PM
malcolmwill Thanks very much for the photos, Rick. These give me a good idea of what was there, and should be easy to duplicate.

A couple thoughts for this thread. First, I like the thought of positive flotation in case of two possible calamities, both of which could no doubt be avoided through proper diligence: 1) failure of hose on through-hull connector, for sink [illegal?] and cockpit drain, and 2) failure of repair to hull from where boat was blown off trailer by tornado [true!!]. I sail in two-hundred feet of fresh water, and if something ever did fail, I'd prefer to be able to stick with the boat. No dinghy or life raft, you know!

Second, calculating flotation is pretty straightforward, if not easy. Weigh the foam per cubic foot, subtract from 59.8 lbs, that's the amount of flotation you've got in fresh water (more in saltwater). Multiply by volume of foam. All the blocks are protected from light and weather, so no problem there. Gasoline inside my Venture? I think not! Sure, sealed air chambers would be neater, but we don't have them, so this is the way you hold enough air (or whatever is in the foam) to keep the boat afloat.

Thanks again for everyone's help with this.
-Malcolm
11-03-2008 03:02 PM
N0NJY Ok, one more. That's it.

Hope those help you (plus the others I already uploaded)
11-03-2008 03:01 PM
N0NJY Ok, here's some. A couple more to follow.
11-03-2008 02:49 PM
N0NJY Here's another little interesting thing. This boat (mine) was built in 1979. Apparently there were no "standards" then?

The manual says:

Quote:
POLYSTYRENE (Styrofoam for example) is the least expensive foam available, but it
will dissolve upon contact with gasoline, is brittle and will crumble when left exposed to
sunlight. Builders who choose to use Polystyrene foams should cover them with
plywood, vinyl or another material, or enclose the foam in compartments where it is not
exposed to abrasion, the elements or sunlight. Polystyrene should not be installed
near the engine or bilges.
This stuff is polystyrene and is not covered by anything. in fact, the rear hold has the gas tanks stored there (on my boat) so, it bugs me this stuff is even there.
11-03-2008 02:46 PM
N0NJY
Quote:
Originally Posted by artbyjody View Post
Actually - the Coast Guard has manufacture / boat building regulations that require usage of flotation foam that must be used depending on design criteria, floatability etc....

Source: http://files.dnr.state.mn.us/educati...atbuilders.pdf

That particular regulation guide is a "easier to understand" version than what actual manufactures have to adhere to.

So - its really not a "marketing spin" per se - but if one has to do it, may as well use whatever marketing points you can get out of it. That document may help to OP calculate how much foam is actually required.
I would like to add a note here.

This is not a "regulation" - this is a "standard".

Inside on the part about flotation the manual says:

Quote:
NOTE:
BECAUSE OF THE INHERENT ADVANTAGES OF LEVEL FLOTATION, ALL
BULDERS ARE ENCOURAGED TO BUILD THEIR BOATS IN COMPLIANCE
WITH THE LEVEL FLOTATION STANDARD DESCRIBED ON THE
FOLLOWING PAGES. BUILDERS WHO CHOOSE BASIC FLOTATION IN
LIEU OF THE ADDED SAFETY FEATURE PROVIDED BY LEVEL
FLOTATION ARE URGED TO CONSIDER INSTALLING THE SURVIVAL
HANDLES DESCRIBED IN APPENDIX D.
This misspellings are not mine. They are the Coast Guard's....or whomever retyped that package for Adobe....

I'd also like to note - I've been in contact with the local Coast Guard Auxiliary - and they've stated quite clearly that neither they, NOR the Coast Guard are "Law Enforcement" officials. lol Not sure why they made that "clear" to me. Oh well.
11-03-2008 02:36 PM
N0NJY
Quote:
Originally Posted by EdWarren View Post
NONJY
Welcome into the fold of the Church of foam questioner's. Live long and sail well.

Ed Warren sailing Lady Warren Mac 26s somewhere South of Omaha
Thanks

Honestly, I question the veracity of whether this stuff could keep a 2000 pound item floating. I am sure that one of the of stuff could help ME float for awhile, but if you are no longer displacing the weight of the boat then the quantity of foam that I found in my Venture 25 sure it's going to keep it completely above water.

In fact, given that most of it is in the stern of the boat, I suspect that the weight of objects plus water, plus the non-air-filled cavities in the front and amidships (where there is zero foam by the way) would do much to keep the boat from making a nose-dive for the bottom.

Anyway, I have a hand full of pictures to post, but having some issues with them. Might have to resize them a bit. I can try to email them to the OP if he wishes? let me know
11-03-2008 06:05 AM
artbyjody
Quote:
Originally Posted by EdWarren View Post
I have sailed for over 40 years, open ocean and currently sail midwest lakes. I have a very low opinion on the value of 'floatation foam'. I think it does a lot more to sell boats than to save boats. If it is there, good, leave it, there is no real imperative to remove it. If not theer,that's ok also. Because of the marketing, the novice is lead to believe this is a major safety item.

Actually - the Coast Guard has manufacture / boat building regulations that require usage of flotation foam that must be used depending on design criteria, floatability etc....

Source: http://files.dnr.state.mn.us/educati...atbuilders.pdf

That particular regulation guide is a "easier to understand" version than what actual manufactures have to adhere to.

So - its really not a "marketing spin" per se - but if one has to do it, may as well use whatever marketing points you can get out of it. That document may help to OP calculate how much foam is actually required.
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