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Bulkheads

Posted: May 28th, '08, 23:36
by Harry Babb
Several years ago I replaced the bulkhead just forward of the engines. At that time I purposely glassed the bulkhead solid so that water could not pass thru and get below the cabin floor.

I have now replaced the bulkhead aft of the engines and am considering blocking the drains that permit bildge water to pass under the fuel tank and enter the bildge area between the engines.

I have installed the 2000 GPH bildge pumps in the forward cabin area...another one between the engines and yet another behind the fuel tank.

What do you guys think about this???? Good idea or not???? Are there any dangers here that may cause me grief in an emergency????

Harry

Posted: May 29th, '08, 00:38
by DRIFTER31
Harry......My 31Tiara came with sealed bulkheads for the cabin and aft of the engines. I think its a good idea and have 2 bilge pumps in each compartment. Its nice to be able to wash/scrub without going into adjacent compartment. Also if you were to run aground the water would have a harder time going foward if a strut was leaking. In the leak scenario you could quickly see which compartment the damage was in by lifting the hatches. Also if a fuel leak in the tank happened it would be contained as well. Troy 31Tiara"DRIFTER" Lafitte La

Posted: May 29th, '08, 07:48
by JP Dalik
Don't know if you gain that much by blocking the 2 sections off like that. We have a solid bulkhead forward of the engines and it really helps keep the funk out of cabin.
The 31 drains alot of water from outside the main bilge channel. Around the decks and hatches for sure. You will still need a way to let the water drain into an area for pump out.
My concern would be that while at rest light on fuel you might begin to puddle water outboard of the fuel tank until it overflows into your oil engine pans.
When you wash out the bilge most of the boat will drain to the center no matter what.
I think I'd keep the open channel under the tank. Maybe run drain pipes through the engine pans from outboard to inboard and get the bilge area as smooth as possible for wiping down.
If ever the mid pump fails at least the Aft pump has a chance to play catch up.

Posted: May 29th, '08, 08:07
by CaptPatrick
Harry,

When the boat is at rest, all bilge water is drawn forward toward the cabin bilge, the lowest spot on the hull being about 6' forward of the engines.

I too block off the bilge forward of the engines, but install a 4" screw out Beckson inspection port at the lowest point of the engine/cabin bulkhead so that the bilges can be quickly re-connected if needed in an emergency.

However, I would strongly advise you not to close off the passage below the tank. The cockpit is the main source of water intrusion into the bilge. At rest, and with the cabin bilge closed off, the midship pump is your primary pump at rest. Running above 13 kt, the aft pump becomes the primary. To close off the below tank passage isolates these two pumps and prevents them from efficiently working as a team.

Three pumps on the B31 is prudent... The ability to be able to have all three pumps in line on a common water path could make the difference between sinking or floating in an extreme situation.

The only place you want to restrict bilge water to is to the cabin, but you need the ability to reconnect when necessary. Remember also that the anchor locker is a water source to the cabin and to truly keep the cabin bilge dry you need to seal off the locker and install a PVC drain pipe back to the aft bilge...

Br,

Patrick

Posted: May 29th, '08, 08:46
by JGomber
Capt Pat,
To install the screw out port would mean opening more of the bulkhead than the relief gap now in place. Is there another alternative if "making bigger holes" gets me nervous?
Since the midship bilge would then become the principal water trap, is an even larger capacity pump (over 2000gph) in order?

Posted: May 29th, '08, 10:35
by CaptPatrick
JGomber wrote:Capt Pat,
To install the screw out port would mean opening more of the bulkhead than the relief gap now in place. Is there another alternative if "making bigger holes" gets me nervous?
Since the midship bilge would then become the principal water trap, is an even larger capacity pump (over 2000gph) in order?
Jerry,

A hole in the wrong place is worthy of concern, a hole in the right place is a necessity. A larger hole for water flow in the bilge is more desireable than a smaller hole.

As FDR said: "...the only thing we have to fear is fear itself."

I consider 2000 gph a standard pump for all three pumps, any larger than that is acceptable, but not necessary. More important that they all work properly & have plenty of battery to draw from...

Br,

Patrick

Image

Bilge Flow.

Posted: May 29th, '08, 11:37
by MikeD@Lightningshack
I too had the same question about 2 years ago.

I cannot not exactly recall my full rational, but I remember that no one could explain adequately the reason for the 2 bilge covers or gulley that run under the tank.

My tubes were in bad shape. They had lots of cracks. They are basically just a thin layer of gelcoat and mat. Maybe they broke from people walking on them while working with me.

I didn't see how they could prevent water from getting to the tank. Anything that came in above the tank seemed like it would likely to stand on the gulley between the two tubes.

Ultimately I just removed them and never looked back. I figured it would give me more distance from tank to standing water, and would be less likely to clog with junk.

As far as the bulkhead forward of the engines. If you fish for tuna blocking it off is imperative. I have had my boat both ways. I sleep on the boat a lot, and after tuna trips this was impossible before I blocked the bulkhead.

I did something similiar to Capt. Pat's arrangment. I also left a large vent open just above the maximum bilge water height that the boat will normally see. This way if there is a pump problem while I am not around water will not build excessively before it overflows into the other compartment.


Mike
www.lightningshack.com


Mike Dolan

Posted: May 29th, '08, 21:19
by Tony Meola
Don't forget one other item. If you close off the access for the water to flow into the cabin area, then you need to install a drain plug in the stern.

Posted: May 29th, '08, 22:13
by Harry Babb
Thanks for the input gentlemen!!!

I never considered putting a PORT in the bulkhead........good idea ! !

I will probably leave the channels below the fuel tank open for water passage.

Mike, I have never been Tuna fishing in DeNada but I think I can relate to fish smell after a fishing trip. You see, a couple of years ago, on our way out to the Gulf we stopped in Mobile bay and threw our cast net to catch some "Shinners".........really stinky little buggers. Well someone put the cast net in a bucket and put the bucket in the cabin......several hours later after we arrived back at the dock I opened the cabin door and nearly tossed my cookies.........YUCKKKKKK

Harry

Posted: May 30th, '08, 08:32
by JGomber
Cap'n Pat,
Just another example of "a picture is worth a thousand eloquent words".
Now I get it. Worst Marine has the screw outs on sale for Fathers' Day. And, I need som more resin. Gonna get on this before it is too hot to hang in the bilges.
Thanks!

Posted: May 31st, '08, 12:32
by DRIFTER31
I do believe sealed bulkheaads helped save that 28Bert from sinking.