Intergral diesel fuel tank

[pescaloco]

hello there,

the project is a 27ft sportfisher - I am buying a new F.R.P MOLDED hull with stringers and bulk heads, the rest of the project will be completed by my self.

so here is the question - the builder states that integral fuel tanks are not coast guard approved - the company that I have paid to consult on the project has suggested that integral tanks are the way to go.

so this is a dilema for me, the hull is desgined to have several bulk heads (per the hull builder) the consultant sugest one bulk head with integral fuel tanks which will maximize space for inboard diesel installation and 200 gallons of fuel in a sadle tank configuration, while stregenthing the hull with no additional bulk head.

my concerns are for the resale value of the boat and the possibility of the hull sides not holding there shape if the hull is removed from the mold with only one bulk head.

any feedback you may have will be appreciated

thanks, mark

[ABoatGuy]

Mark,

Diesel fuel tanks - the USCG doesn't get involved with diesel fuel tanks in recreational boats. If executed properly the integral tank should be ok. They are approved by most societies if built correctly.

Since you have a completed hull, the bulkhead placement (the number, sizing and spacing) are dependent on the existing hull structure. i.e.: You have existing FRP panels that have to be supported at some intervals such that their deflections under load are within limits.

What does all that mean? My thoughts: if the original builder had a well engineered structure I wouldn't stray too far from his structural plan without some justification. That said, there is more than one way to skin a cat. If the consultants have taken a good look at the existing structure and can demonstate that their plan is based on some reasonable criteria they could also be fine.

It would probably be a good idea to ask your consultng company what they are basing their structural design on, if they have determined the stiffness of the existing hull laminate etc.

A second opinon wouldn't hurt. Your putting a lot of your hard earned dollars into this project. If the basic structure seems really sketchy or unusual this isn't the place to save a nickel. It might bite you in the tail later.

[pescaloco]

thanks, for the reply

the hull builder stated that f.r.p. tanks were not coast guard approved and he did not recommeded them (so this led to some concern on my part) but if it is an exceptable practice that is good.
I am most concerned about legality and resale if that time comes some day. I would hate to have a surveyor say that the tanks were not legal.

the reason integral tanks are recommended by the consultant are two fold
1 to allow an easy to service remote mounted v-drive - cummins diesel install
which will allow for best weight distribution
2 to provide a very rigid hull structure through the integration of fuel tanks and fish boxes into the hull.

my statement about hull intergrity when pulled from the mold with only one bulk head was more my concern than the hull builder - I was just affraid the hull sides might not hold shape - but I guess it could be braced with 2x4

any additional feedback on original question is welcomed

thanks, mark

[Ike]

Pescaloco,

I worked for many years in the Coast Guard Office of boating safety regulating manufacturer of recreational boats. Integral tanks are not allowed in boats with inboard GASOLINE engines, BUT the Coast Guard does not regulate the fuel tanks on diesel powered boats.

The American Boat and Yacht Council sets voluntary industry standards for recreational boats and has a specific standard for Diesel Fuel SYstems (H-33)and this is what the manufacturing industry follows for diesel boats. H-33.10.1 specifically allows integral diesel tanks. In fact integral diesel tanks are very common. Even an esteemed bulider like Hatteras Yachts has integral diesel tanks on their yachts.

[pescaloco]

thanks, for clearing up my concerns. not sure why my builder stated what he did ??

mark

[Ike]

A lot of people get confused over what is a regulation and what is an industry standard. Also people often believe what they want to believe.

[gerard baladi]

I believe that to have an integral diesel tank on a small boat would be a bad Idea.
You may need at one time or another to access either for maintenance or clean (sludge).
Hatteras have most probably manholes to access.

[catmando2]

The cat i'm building at the moment has underfloor tanks. All baffles,ends and floors[ sole] are 9mm marine ply and 250gsm glass with epoxy.

This is an integral part of the structure.

Make sure epoxy not polyester is used would be my recomendation.

Dave

[pescaloco]

catmondo, that looks pretty similiar to the set up that was recommended to me, I thought I read that epoxy could have issues for fuel tanks ( probably just for gas)

do you plan to have the sole to be the top of the tank ? that is one point that is not clear to me. I believe what I read about integral tanks stated that tanks would not be part of a hull structure such as bulk heads or deck (sole)
structures sould be supported (with out the aid of the fuel tank) able maintain the integrirty of the structure if the tank were not there.

mark