Gas tank in engine compartment

[hoxha]

As you can see, we are overhauling a 1980 so called 'grenzboot' a German DDR patrol boat. I don't do it by myself but have help from yachtbuilders.

The engine compartment is pretty big, so when we replace the Russian V8's with 2 Mercruiser 4.3 MPI 220hp's there will be lots of unused space.

compartment size: width: 2,7 meters length: +2 meters.

The yachtbuilder suggested we could place a rust free steel 350-400 liters (about 95 gallon) gasoline tank in the engine bay, placed at the utmost front of the engine bay. Normally the tank is situated belowdeck.

However, I have some reservations about this placement. Mostly because I could not find any examples of a gasolinetank in the engine compartment.

engine compartment contents:
-automatic fire control
-2 MPI injection engines (no fumes)
-electrical installation (electric equipment like an inverter are all certified for use in engine rooms and all boxed in)
-cable harnesses

What do you think, am I creating a big safety issue. Or is it good design?


build process here: In Dutch:-)
http://www.staatsgeheim.com/category/grenzboot/

[anthony goodson]

There may also be a trim issue.

[whitepointer23]

my boat has 2 200 liter fuel tanks in the engine bay with 2 v8's. it is standard layout from the factory.

[hoxha]

thx, good to hear. What type of boat would that be?

[whitepointer23]

savage lancer 26 , look up boatsonline australia on google and put savage lancer in the keyword search, there are a few on there.

[CDK]

Placing the fuel tank in front of the engine is not uncommon.
The Norwegian Draco boats with 25-30 ft. hulls all have the fuel tank(s) there, but separated by a glassed-in bulkhead to prevent the engine bay from flooding in case of a leak. A sturdy plywood lid is mounted over the tank to protect the plumbing and tank element.
The bulkhead provides a convenient wall to mount small peripherals like fuel filters/water separators, automatic fire extinguisher and emergency bilge pump.

Battery banks are placed left and right of the engines.

[hoxha]

Originally Posted by CDK

Placing the fuel tank in front of the engine is not uncommon.
The Norwegian Draco boats with 25-30 ft. hulls all have the fuel tank(s) there, but separated by a glassed-in bulkhead to prevent the engine bay from flooding in case of a leak. A sturdy plywood lid is mounted over the tank to protect the plumbing and tank element.
The bulkhead provides a convenient wall to mount small peripherals like fuel filters/water separators, automatic fire extinguisher and emergency bilge pump.

Battery banks are placed left and right of the engines.

Thanks all. We are going this route. Will post the pictures:-)

[Tad]

Originally Posted by CDK

prevent the engine bay from flooding

WITH HIGHLY EXPLOSIVE GAS!

Absolutely add a gas tight bulkhead between the engine compartment and tank compartment.........

[hoxha]

Originally Posted by Tad

WITH HIGHLY EXPLOSIVE GAS!

Absolutely add a gas tight bulkhead between the engine compartment and tank compartment.........

I figured that one out. We are making a special compartment. In case of a major fail we have a nice gasoline hot tub. But always better then letting it leak all over the engine bay.


Thinking of placing Statx automatic fire extinguishers, and perhaps a fume detector as well.

[Ike]

Placing a gasoline tank in the engine compartment is pretty much standard procedure in US built recreactional boats. As long as you follow ISO standards (or RCD) then it should be a safe installation.
Three things are critical;
Using ignition protected electrical equipment (standard on Mercruisers).
Using good quality fuel fittings and marine fuel lines.
Compartment ventilation.

All of this is contained in the RCD or ISO standards. Or you could follow ABYC standards which are nearly identical to ISO.

Also using an automatic firefighting system adds another level of protection along with fume detectors and alarms.

Keep us posted.

[CDK]

Originally Posted by Tad

WITH HIGHLY EXPLOSIVE GAS!

Absolutely add a gas tight bulkhead between the engine compartment and tank compartment.........

That actually happened to me once.
Seawater ate a hole in the bottom of the aluminum tank and almost 60 gallons of gas were sloshing in the bilge; the smell was breathtaking.

My greatest fear was the spark in the bilge pump switch, so I attached a thin cord to it and pulled the cord from a safe distance.
Most of the fuel was recovered in a small rowing boat with a hose plugged into the through hull.

[anthony goodson]

Well at the risk of upsetting those who's advice I normally respect ,I have to be the small still voice that is not happy with this .From the photo it would appear that there is adequate room further forward ,under the floor ,in a bund,so why take the chance. Gasoline in a boat can and will kill you, a fire suppression system will not deal with an explosion and gas detectors only help if the leak is progressive. I am aware that many small cruisers are equipped this way I have owned and worked on them ,but this is normally to do with the best use of space. Also as I said earlier if you have a tank who's weight can vary between very little and half a ton ,even in a boat this heavy ,if it's easy, put it nearer the centre of longitudinal flotation. Just my five bob's worth.

[Ike]

You are absolutely right that it is better to isolate a gasoline fuel tank away from the engine compartment. Many issues go away if the tank is elsewhere. However, that was not his question.

I was saying only that it can be done but must be done right.

Putting it in it's own space where there is no electrical equipment and no need for speficic compartment ventilation is better.

[michael pierzga]

And as was noted earlier...a gas tank aft sinks the stern of the boat. If aft, in the machine space , is the only position available guess you must do what you have to do...but I would prefer keeping ballast...fuel...amiships and the boat on its lines. .

[hoxha]

Originally Posted by anthony goodson

Well at the risk of upsetting those who's advice I normally respect ,I have to be the small still voice that is not happy with this .From the photo it would appear that there is adequate room further forward ,under the floor ,in a bund,so why take the chance. Gasoline in a boat can and will kill you, a fire suppression system will not deal with an explosion and gas detectors only help if the leak is progressive. I am aware that many small cruisers are equipped this way I have owned and worked on them ,but this is normally to do with the best use of space. Also as I said earlier if you have a tank who's weight can vary between very little and half a ton ,even in a boat this heavy ,if it's easy, put it nearer the centre of longitudinal flotation. Just my five bob's worth.

Made me think. Of course there is going to be a thick firewall between the tank and engine room. With the removal of the Russian equipment lots of weight in the back is gone and there is a wealth of space. Even for a double walled foamed up firewall to make it a separate compartment. This wall should buy time in case of engine fire.

On the front we are making the boat heavier with an interior, heating/refrigirator/chairs etc. So it should even out nicely empty or full.

Putting tank under the floor is a bit tricky. Because in the original boat, the aluminium tank WAS the floor. There are issues with height, space, fixing the tank, the fuellines and the fuel line for filling the tank. It can all be done, but in the end comes down to cost... about 5-10x more.