Underdeck questions

[Bullshipper]

I have some general questions, that might make individual threads on there own, but I would like to star lumping some together.

Underdeck Ventilation
Is it not more desirable for air to enter the underdeck area near the bow to ventilate the underdeck area to remove accumulated fuel fumes, evaporate accumulated water, dry out oder producing molds? Could a standard blower under the bow plate or naturally asperated scoops be placed forward to force dry air to the stern where it could exit through a riser venting under the rail to prevent water intrusion? Would this not breal the sealed chamber problem that can cause explosions when fumes are sparked by a bad electrical connection or welding rod?

Underdeck washing
Some salt water must be getting down below. I have been playing with the idea of using a spray on foam, just thick enough to deaden chamber noise amlification, but want the sponsons on a cat we are designing to freely drain down an open keel channel to each sponson drain. The narrow sponsons is not to tough to wash if you leave a hacth forward and behind the gas tanks so that a you and use a hand sprayer to shoot each sponson inner wall.

Are washouts recommended? Any ideas on what foam might be good to attach it self to alloy?

Gas Tank Drain Line?
I like the idea of being able to completely drain fuel tanks to remove crud and stale gas from time to time.

So I have been thinking of running a seperate 1/2" fuel line with a plug on its end down to the transom so that it could be fished by hand out the main drain holes to fill bottles with a screen, and be used in my truck on the way home, or disposed of.

Do you see any problems with this idea?

[peterbo3]

Underdeck Ventilation
Is it not more desirable for air to enter the underdeck area near the bow to ventilate the underdeck area to remove accumulated fuel fumes, evaporate accumulated water, dry out oder producing molds? Could a standard blower under the bow plate or naturally asperated scoops be placed forward to force dry air to the stern where it could exit through a riser venting under the rail to prevent water intrusion? Would this not breal the sealed chamber problem that can cause explosions when fumes are sparked by a bad electrical connection or welding rod?

Bull,
If you look at any commercial vessel in survey you will see that the ventilation system in the engine room or machinery spaces is an "extraction" system. Air is sucked out by fans & fresh air comes in through inlet pipes.
Depending on the underdeck volume & compartment numbers, you may need many or few extractor systems.

I would not worry about the washing or the spray on foam. The foam may hide cracks or get waterlogged. The second fuel line is a good idea. We had a similar system on our trawler for every diesel tank.

[warthog5]

So I have been thinking of running a seperate 1/2" fuel line with a plug on its end down to the transom so that it could be fished by hand out the main drain holes to fill bottles with a screen, and be used in my truck on the way home, or disposed of.

Where would this line enter the tank? Have you checked the Standards that tanks are bound to?


Here again some of these questions are strange to me.

I don't know if your testing our knowledge or you truly just don't know and they are legitimate questions?

I would like to think that someone thinking of building a single boat or going into production would have a better understanding of these questions.

Have you ever played with Flotation Foam? Have you ever seen what happens to it with older boats that have leaked water into it for years and years on end?

[Bullshipper]

[quote="warthog5"][quote]So I have been thinking of running a seperate 1/2" fuel line with a plug on its end down to the transom so that it could be fished by hand out the main drain holes to fill bottles with a screen, and be used in my truck on the way home, or disposed of.
[/quote]

Where would this line enter the tank? Have you checked the Standards that tanks are bound to?

Have you ever played with Flotation Foam? Have you ever seen what happens to it with older boats that have leaked water into it for years and years on end?[/quote]

Warthog,


FUEL
Thanks for bringing up the standards point Bobby.

I have been hoping that I could just purchase plastic tanks to drop in my sponsons as I consider aluminum tanks more difficult to build. The plans I have spell out the fuel system, but no consideration was given to the idea of draining or flushing, si I thought it wounldn't hurt to ask for some input.

As far as the drainage idea goes,
I first considered putting a tee in the fuel line prior to making its rise to the fuel filter, but gravity draining is a problem due to the spring on the anti siphon valve. So again I am faced with using a dedicated pump that could just as easily suck out the tank from the top.

So I am planning on a tee at the outlet prior to the AS Valve feeding a dedicated gravity drain line along with the fuel line going to the motor.

FOAM
I have never laid foam.

But I have found that it tends to breakdown and get soaked by the time I find it near my bilge pump.

[welder]

Jeff, some plastic tanks can permiate [ spl ] fumes into your hold . If you can go alloy on the tanks also.

I like the idea of the drain , I whish I had one to drain the fuel out for loooooong road trips.