that big hole in the bottom called bilge

[Mike C]

it collects everything and it has a tendency to small and each time I clean up I find things I never knew I had lost. But why do I need it so big and so deep anyway. Has anyone just --carefully-- used expanding foam and then sealed it over with water tight fiberglass. It seems like a great idea.

[Oswego John]

I would suggest keeping floatation high and ballast low.

O J

[Steve Laume]

I sometimes wonder if our bilge is too small. The back portion of our bilge is consumed by the holding tank on our 1984, CD-30. I would much rather they put the holding tank up forward somewhere to shorten hose runs and make it easier to rig a holding tank pump out with no additional thru hulls. I would also like to have the entire bilge open. The bilge acts as an insurance policy for the rest of the boat. If you do take on water for any reason it would be very good if the bilge had the capacity to contain it while you worked out a solution to the problem. If you do fill your bilge and anything bad happens it will immediately flood your cabin sole. You would tend to notice this but at that point you would have a lot of water and weight sloshing around up realativly high in the boat. And if you do feel like filling it, it would be better to fill it with something heavy like beer, Steve.

[Neil Gordon]

And if you do feel like filling it, it would be better to fill it with something heavy like beer...

Expect that you'll lose the labels if you store bottles. I agree with storing heave stuff low, though. I store tools, heavy spares and the like under the floor boards. Fitted out so the bottles are secure, it's a good place for a wine cellar, too.

Big advantage of the deep bilge and in particular the sump is that it doesn't take much to trigger the float switch. Six inches of water in the sump is a lot better than an inch over the floor boards.

[Mike C]

I would suggest keeping floatation high and ballast low.

O J

there is no floatation for anything that is sitting inside the hull , only when it gets in the water. A block of styro foam is worth nothing as floatation untill you fill the boat with water and ballast is still in the same low place

[Tom Keevil]

I have often thought our bilge would be great for storage, but it has poor access through the sole hatches, and it's not clear what sort of devices I would put down there to hold things in place. What have you folks done to keep stored items from rolling down to the bilge pump?

[Rollergirl]

I'm for filling in the bilge, and I'm in good company. It's not about the expense and effort, it's about safety.

Consider that a deep bilge would allow more time to fix a leak before economic damage (ruined furniture, sinking at the slip, confusion over wether your guests are getting your limited supply of good beer as opposed to the other stuff you normally serve "friends", etc.) and it is easy to make a case for a huge bilge capacity.
But consider instead being pooped out of tow range of BoatUS.

Buoyancy comes from having a lighter vessel then the water is heavy. Once the vessel is filled with enough water to exceed the Buoyancy, you sink. When your buoyancy is totaly dependant on free air (as opposed to, say, foam) the free air flees. The foam, too dumb to do otherwise, floats the boat.

A floatation plan that puts the floatation low in the boat keeps the gunwales higher for the second wave (and the third, fourth, etc.) better then the floatation that only comes into play when the boat is almost submerged.

Zeke Durica, the builder of today's new non-self-bailing Ensign, is putting foam in the bilges and other lower areas of the boat. Zeke lost an Ensign during a knockdown a few years back (sank in 40 feet of saltwater, and worse, he lost the regatta), and figured out the best way to prevent a loss like this again is below-the waterline-floatation. Makes great sense to me.

But where, Bill, I hear you say, do I put my beer?

Beats me, bro. But then ,I don't drink beer. Anything with a single digit alcohol content isn't worth storing. A quart of good brandy is like a barrel of beer. And tastes better.

Bill

[Neil Gordon]

I'm for filling in the bilge, and I'm in good company. It's not about the expense and effort, it's about safety.

If the bilge is filled in and 100 gallons of water flood the boat, the effect is the same whether the water sits in the bilge or on top of the foam. If filling the cabin to sea level will cause you to sink either way, where's the safety factor?

[Steve Laume]

I can't say that I have done the math but You would probably have to fill most of the boat with foam to get her to stay awash. If you wanted her to float on her lines better fill her all the way. If you start by filling at the bottom and you are worried about a boarding wave, that first one is going to greatly decrease your stability if you are keeping all that water weight unconfined above the cabin sole. Better to keep the hatch closed in conditions that may allow waves to board. Once again this is an area where I would not question weather I knew more about boat design than the original designer of our boats. That bilge is there, unfilled with foam, for a very good reason. Even if I didn't have any idea what the designer had in mind when he designed it that way, I would not eliminate it. When we used to go winter backpacking we always carried a small flask of Yukon Jack because it was more efficient than the same amount of brandy. Boats are much more forgiving, Steve.

[rtbates]

If you reduce the bilge size you'll know if you take on water sooner, because it'll be over your cabin sole! Not a good idea.
A better idea is a bilge pump alarm or just pay attention and listen for the bilge pump cycling. That's a better way to know you're taking on water than having it ankle deep in the cabin.

[Oswego John]

I would suggest keeping floatation high and ballast low.

O J

there is no floatation for anything that is sitting inside the hull , only when it gets in the water. A block of styro foam is worth nothing as floatation untill you fill the boat with water and ballast is still in the same low place

Hi Mike,

I think that maybe you have possibly misinterpreted my suggestion about keeping flotation high and ballast low. Let me try to explain my viewpoint more clearly.

I don't think that there is any question that the keel ballast is low. The ballast that I was referring to was other things that are often found on many sailboats. Among these, might be included battery banks, various fluid holding tanks, anchor chain, tools, spare parts and jury rigging, if any.

My contention is that if this extra ballast is above enough flotation to support the boat and it's contents, should the hull take on a dangerous amount of water, there might possibly be a seesaw reaction and thereby decrease seaworthiness.

It's only my unproven thought, nothing more. It is my feeling that any additional flotation should be higher than the ballast below it. This would help prevent top heaviness and help maintain a low center of gravity.

I have seen some smaller boats fitted out with flotation between the outer hull and the inner skin. Also flotation under seats and sealed air chambers in the prow and stern. Many aluminum hulls have this built in flotation.

Believe me when I say that I think that flotation is a good thing. But I think that it should be higher than lower.

Best regard,

O J

[marka]

John is correct. Water in the bilge will reduce buoyancy but will not adversely effect stability.

An equal volume of water taken on by the boat but displaced by faom in the bilge will both reduce buoyancy and adversely effect stability.

As a side note, "Tall Ship Down" is a really good written account of the loss at sea of 6 different sailing vessels during the last 50 or so years. In 3 of these cases. the loss was due in part to reduced stability brought on by ill-conceived changes to either the rig or operational practices.

Under no circumstances would I get on a boat that had a design change like this implemented without proper testing of the effect on stability while taking on a volume of water equivilent to the bilge capacity.

[Dwain Douglas]

For foam or any floatation to have any value, there would have to be enough to keep the boat from sinking, otherwise the foam will just 'go down with the ship'.

You would need well over 10 cubic feet of foam for every 1,000 pounds of boat... a LARGE amount of space. If you have only 9 cu ft of foam... the foam will go down with the boat no matter where it is placed... high or low.

When the boat gets "Pooped", the 100 lbs of water that went down the hatch is still 100 lbs, and it is sitting higher (the water not the boat) because of your foam.. bad for stability (more likely to sink), bad for the interior, ... bad foam, good bilge.

Dwain