Fuel tanks for V-dory

Questions about modifying a design

Moderators: ttownshaw, billy c

StefanK
Posts: 11
Joined: Sun Mar 23, 2008 10:44 pm
Location: Bellingham, WA

Fuel tanks for V-dory

Post by StefanK » Fri Jun 13, 2008 7:35 pm

I'm having a dilemma. The frames of the V-dory are spaced 16" on centers allowing approximately 15 1/4" between frames. I was planning on raising the fllor with 2 x 6's so I could accomodate a fuel tank below deck above the bottom battens. i would like to put the tank amidships with a the fill the side. The problem I am having is that no one makes a standard tank 64" L x 15" wide x 8" high. Any body have any suggestions? I could always have a tank welded up, but I was hoping someone has dealt witht this in the past. I'm trying to keep the weight off the stern, I figured the 384# outboard engine is enough on the transom.
:?
StefanK
Bellingham,Wa

upspirate

Post by upspirate » Fri Jun 13, 2008 8:18 pm

I would go with the custom welded tank.probably not that much difference between that & a standard tank.

Check it out,it's probably not more than $110 difference if that.

Then they can out fittings where YOU want them & in the long run,you will be much happier.

If you look at the overall cost of the boat,motor trailer electronics,it's small money& you will be happier. :wink:

User avatar
Bill Edmundson
Posts: 11517
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Post by Bill Edmundson » Sat Jun 14, 2008 7:10 am

When I bought golf clubs, There was a set of Hogan's that I wanted. Spalding made a copy cat that looked just like them. Hogan... Spalding... Hogan...Spalding $200?

A friend of mine said, "Spend the money. You'll forget about paying for them. Every time you stand over the Spaldings you'll think, I wish I'd got the Hogans."

I spent the money and never regretted it.

It applies to boats, too.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

User avatar
kens
Posts: 4664
Joined: Wed Nov 12, 2003 5:25 pm
Location: Coastal Georgia

Post by kens » Sat Jun 14, 2008 7:34 am

I am soon to need custom welded tank also.

Does anybody have a list of fabricators/vendors that make tanks?

User avatar
Bill Edmundson
Posts: 11517
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Post by Bill Edmundson » Sat Jun 14, 2008 10:15 am

Ken,

You might try http://www.rdsaluminum.com/

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

DonBing
Posts: 151
Joined: Sun Nov 16, 2003 9:52 am
Location: Northeast Ohio

Post by DonBing » Sat Jun 14, 2008 11:45 am

StefanK-- I am building the Hunky Dory and have mulled over the same dilemma. Couple questions and observations though.

Are you sure of the dimensions? I have 55" chine to chine. Your beam is 6" wider than the HD and if that is proportional and you raise the floor a true 6" then you have capacity for 24 gal. I don't thinks that's a lot of additional weight for that boat. Especially if you have that add'l 6 inch width sitting on the water. My ob is also about 380# and it sat in the water nicely level. I've since added a forward cabin which will offset the fuel load a little. If the 64*15*8 dimensions are doable then you get 33 gal. But you could lose some off either calculation (doesn't the tank have to be bedded in something?)

I have put some framing and a hinged platform on either side of the motor well each of which will accomodate a 12 gal tank. When installed and full I'm confident I won't see any change in the repose of the boat.

Long post but when I first read your idea I wanted to check the possibility for my boat. Healthy expense for a small difference, I think. The other possibility is build the boat, finalize the cockpit layout and see what space you want to give up for a fuel tank(s). Play with some weighted arrangements and then make a choice. The below deck tank is a simple retrofit, I would think. Good luck with it.

Don

upspirate

Post by upspirate » Sat Jun 14, 2008 1:22 pm

Here is a builder of tanks& other marine stuff in the Tampa bay area of fla:

http://www.seamount-mattson.com/

StefanK
Posts: 11
Joined: Sun Mar 23, 2008 10:44 pm
Location: Bellingham, WA

Fuel tanks for V-dory

Post by StefanK » Sat Jun 14, 2008 11:45 pm

Don,

Sounds good I was concerned about what to do with the 18" or so on either side of the motor splash well. The other reason I raised the decks is I also wanted to put a cabin on it and was concerned about seeing over the bow. I didn't want to climb up a ladder to drive. I'm finishing the interior of my boat like Steve Lippincott with self bailing scuppers on the back. the finished interior floor height will be 2" above the designed water line. I'm also sloping the floor at 1/2" per 10 feet so any water naturally will collect in the back. The gunnel area will be widened with side decks 12" wide from the stern to the bow, I was concerned about a person leaning to far out on the flaring sides and falling out, so the 12' wide decks will help offset that.
The sad truth is most of the cabin plans were drawn for the Hunky, Big and Little Hunk without considering the V-dory. So, I'm going to wing it. All the plans for the cabins don't mesh with the frames on the V-Dory on any of the designs A-E. I do know that the trunk cabin top as it passes under the windshield becomes the dashboard.
I've pretty much decided on having a aluminum tank welded up, I computed at 7.48 gallons per cubic foot of space I should have a 29 gallon tank that is only 7" high which gives me room for the sender and pick up tube. The floor over the fuel tank will be gasketed in case I need to pull it in the future, similar to a Boston Whaler. I also desicovered Red Devil makes a single expanding foam that is waterproof when cured, I'll either bed the tank in foam or SikaFlex. The space adjacent to the motor splash well can hold a spare 6 gallon reserve in a polyethylene marine fuel tank and the other side will probably hold a baitwell.
Stefan

Kevin Morin
Posts: 738
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Aluminum tanks cost savings

Post by Kevin Morin » Sun Jun 15, 2008 11:04 am

StefanK, DonBing, kens

One-off aluminum tanks can be expensive compared to the cost of stock designs from a tank supplier that makes the same model repeatedly.

Obviously the labor to layout and cut that tank's panels, individually, instead of in dozens or hundreds of pieces, means the time for hired fitters is greater. But you may well build your own tanks and simply find a shop to weld them.

Aluminum is cut just like plywood (different blade in the saw helps) and can be filed, sanded, and ground on with normal wood working tools and some small adjustments to technique and lubrication.

So if you find a local shop capable of aluminum TIG (most suitable for tank welding) you may be able to save costs and get the exact tank you want by doing all the cutting and fitting. Then when cut, fit, edge prepped, you can turn the parts over to the shop with a decent sketch and they may be willing to do the welding?

I have built countless tanks of plate aluminum over the years and it was common to quote someone the full cost of a finished tank then learn they didn't want that level of expense.

I have also welded several tanks designed and cut by wood workers with excellent skills who didn't have welding experience but brought me the cut pieces to tack and weld.

This method puts all the decisions on you as the tank's 'builder' and the fab. shop is not responsible for any design errors, but there can be some real cost savings. The more unique the shape of the tank or the more unique the fittings are arranged, the more costly an individual tanks' value. By using your own tools and taping the tank's panels together as you build, you can build one as easily as you could of thin plywood.

Many rectangular tanks can have the majority of the seams bent in a press brake, so a local sheet metal/welding shop that has the capacity to bend aluminum will further save on welding time and make the shape self-supporting by use of the bends.

If you travel around to pick up the plate/sheet then deliver it to a shop to shear, bend and then move those parts to a welding shop you've eliminated a large overhead value in the tank. The time to cut the panels your self is very small, but knowing the design and mocking up as you go will allow you to save the value of someone else's labor and you can, hopefully, hire just that part of the work you're not equipped to do?

Bedding unpainted aluminum tanks in urethane based foams is folly. The aluminum cannot resist acids and the foam breaks down into formic acid (from formaldehyde ) and will pit aluminum in a bilge mount. If you paint the tank, then the "foam-juice" can't get to the metal as easily.

I'd recommend the tank be: Painted if at all possible; Mounted on strips of ridged vinyl carpet runner with 5200 bedding; bolted to the transverse frames four (4 ) times fore and aft along the tank's long sides using SS bolts and plastic washers & sleeves to isolate the tank's mounts from the hull and fasteners.

I'd also recommend a prominent grounding lug below the fill riser so you can put an alligator clip lead from the tank's fill riser to the pump or pump nozzle to insure there is no potential; but most folks think that isn't necessary.

cheers,
Kevin Morin

catman4926
Posts: 24
Joined: Fri Nov 14, 2008 6:29 am
Location: Mobile,Alabama, USA

Post by catman4926 » Sun Nov 16, 2008 5:10 am

Kevin,

In reading these post is it not permissable to use a poly tank between the huul and the deck? Just wondering newbie to this boat building

Kevin Morin
Posts: 738
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Tanks in a Skiff

Post by Kevin Morin » Sun Nov 16, 2008 5:37 pm

catman4926,

I don't see why you can't use any material tank, (that holds fuel) and where to put the tank is a matter of the skiff design and the level of effort you want to expend.

My remarks were trying to assure the wooden boat builders, here, that they already had 90% of all the necessary knowledge, skills and tools to build their own aluminum tanks in a manner that would conserve costs.

It was my impression that one of the issues being discussed was the one-off nature of the tanks required- not that one material or another were needed. I implied from the first few posts that shallow and wide tanks weren't stock tanks, and I'd expect that to be true in all materials that tanks are made?

If you use a plastic tank then I'd expect you'd need to make sure it was mounted on a flat surface for support as they aren't usually suspended as would be good practice with an aluminum tank. So this implies a decking or sole over the transverse frames below the deck to hold the tank.

cheers,
Kevin Morin

StefanK
Posts: 11
Joined: Sun Mar 23, 2008 10:44 pm
Location: Bellingham, WA

Fuel tank for my V-dory

Post by StefanK » Sun Nov 16, 2008 7:38 pm

Well after considering the pros and cons of aluminum construction and trying to stuff the tanks under the floor (only about 6"), I went with raising the floor to just above the waterline and making the boat self bailing. I added a commercially built 27 gallon topside tank which I disguised as a deck bench that sit directly in front of the motor well. I installed a 2008 4 stroke 90 Mercury and it sips 2.3 gallon an hour at cruise (19-21 knots) 4500 rpm. She will run 39 knots wide open and slurp 7 gallons an hour. So far on my longest run about 54 miles I used just under 1/2 a tank. Whatever you decide it will be trial and error. I didn't install a water sep because most of the fuel can be treated or will be used in two weekends. I definitely would have if I installed a 40 gallon or larger tank.
I have the boat finished and on the trailer.

upspirate

Post by upspirate » Mon Nov 17, 2008 7:57 am

for $30 or so, a water separator is cheap insurance...you'd be surprised at how much condensation,bad gas,etc you can pick up& with today's fuel injected engines, you need lean fuel.

They also filter more than just water

jdhogg
Posts: 19
Joined: Mon Jul 13, 2009 8:45 am

Re: Fuel tanks for V-dory

Post by jdhogg » Sat Aug 15, 2009 12:59 pm

check out www.summitracing.com they have different sized tanks for race cars and might just fit what you need,

StefanK
Posts: 11
Joined: Sun Mar 23, 2008 10:44 pm
Location: Bellingham, WA

Re: Fuel tanks for V-dory

Post by StefanK » Sun Aug 16, 2009 12:13 am

I ran a topside 26 gallon tank hidden inside and under my fishbox, but in the Pacific NW
it's always a good idea to have extra. The other main decision changer was trim. The boat was riding very low in the back. The 2008 90 four stroke weighed 400# and 26 gallons of fuel right in front of it added another 250. I decided to design and have a aluminum fuel tank fabbed up and i put it under the bunk in the cabin, just forward of the center of bouyancy. The tank's capacity is 44 gallons. I ran the fuel line under the deck and it passes through a watersep filter before the engine. I also yarded out my motorwell, it took up too much deck space. I now have a flush transom, glassed on both sides. I also installed 1/4" 6061 aluminum plate through bolted to provide extra lip stiffness. This result was from a crack I noted at the floor of my motorwell where it attached to my transom. Transom and motorwell were built to the plans. I'm still finishing up the v berth fuel tank mod. Just glassed the top of the bunk plywood. Fuel tank will be vapor isolated.

Post Reply

Return to “Design Modifications”