Boat Builder Central - Builder Forums

Hello, so as we finish glassing in our stringers, we've started to think about the upcoming steps, namely the fuel tanks/system. Our first question would be whether we should go with HDPE or aluminum tanks, and if you know of any ready made tanks that would fit into the P19. We have our holes cut in the stringers for chase tubes etc as marked on the plans, now we just need to source the tank. Also, the plans seem to show two tanks end to end with a frame in the middle, but I don't really see how that would work. Any help would be much appreciated.

The fuel tanks are one of the toughest trade-offs you make. The aluminum tanks will not stand up forever with any salt water in the bilge. However, you can get them built in just about any configuration. The plastic tanks are tough, but they expand about 3% the first time you fill them and they need ventilation since they degas. Both are available from several sources if you check Google.

The bigger question is how to mount them. First of all there is the 3% expansion to consider. Also, the approved gas fill hoses are extremely stiff. I am not sure how you plan to route the lines though the middle of the stringers from a port on the top of the tank. I was not going to cut large notches in the top of the stringers, since they are the main structural element in the hull. I ended up routing the fill lines along the bulkheads above the sole.

The next question is the gas feed line. You want both pickup lines in the rear of each tank, since the bow will be raised most of the time. Since I had already bought a plastic tanks with the fill port and pickup on the same end of the tank, I have one tank which is not "good to the last drop" as they say. For awhile I thought about replacing the front tank with a custom build, but got so used to it I compensate automatically for the loss of range.

Lastly, you may not need two tanks. I allow 5 miles to the gallon when leaving home, although you can usually get more. In my case, that means I need a fill up for every two trips around the island or I get nervous about paddling home. If your trips are shorter and your gas station closer, you might get by with one tank.

Good luck. Most of the rest is easier.

Thanks for the reply Eric, Would it be possible to go into a bit more detail about how you routed your fill lines? we're thinking about going with a custom aluminum tank for customization, I also like the idea of baffles to prevent too much fuel from sloshing around and unbalancing the boat. Also, Jacques if you have any input regarding the fuel system in general that would be much appreciated as the plans do not provide much detail on the system. I got a quote from a custom tank builder, is 73"x18.5"x9.5" too long of a tank? We've given up dropping the floor between the stringers in the pilothouse as we need some more weight forward to compensate for the bracket. All in all the fuel system generally leaves me scratching my head as I am pretty much only used to portable tanks etc.
Thanks
Liam.

Just one slight correction to Eric's post. The new plastic tanks no longer outgas due to a change in the laws.

If you are going with aluminum I think there is a good choice available almost off the shelf which will avoid the mistake I made. I used the Moeller Marine Below Deck Permanent Fuel Tank (25-Gallon, 47" x 18.03" x 7.5") which is sold by Amazon. Notice that the fill tube is straight up and the fill and fuel pickup are on the same end. This is not problem for me on the rear tank, since I have a full width bench seat on the back of the boat that covers the short exposed section of fill line. However, I am assuming, that you will want most of your fuel in a front tank, to counterbalance the bracket. In that location getting my fill line to the port side deck involved a path above the sole against the bulkhead.

One good solution for you is with http://www.rdsaluminum.com/marine-stock-below.html. Their 59181 - 30 gallon, Belly Tank has a horizontal fill inlet and a rear pickup. If asked, they will point the fill to the side where you should find a decent path under the sole. You will then have 30 gal supply, good to the last drop. As for the rear tank, it depends a lot on the range you want but you might be satisfied with a smaller backup supply that is easier to mount.

Lastly, don't forget the antisyphon barbs on the fuel lines.

P.S. Forget the baffles, you don't need them. The total change in balance from fuel going from one end to the other in the tank is small compared to the wave action that is causing it.

Small tanks do not need baffles, large ones are built with baffles.
The location of the tank matters: put the tank CG under the feet of the skipper, just behind the console. If you have an extra heavy engine or a bracket, move the tank somewhat forward.
The material is up to you, I like rotomolded tanks like the ones from Moeller.
Put the tanks on platform, strap down. Follow the tank manufacturer instructions, most metallic tanks will require a neoprene pad. Same for fill, venting and other connections, tanks come with instructions unless it is a custom tank but even in that case, the fabricator will help you.
Or see:
http://newboatbuilders.com/pages/fuel.html

Also if you go aluminum check Speedytanks.com they coat there tanks which will last longer. They also will put the type and place the fittings where you want them. If you can't find what you want they will build it for you it, Cracker Larry has bought several tanks from them.

I used Speedy Tanks for my little 5 gallon tank. they were very nice and accommodating throughout the process, and built my tank exactly as I requested. I found another supplier, and received one of their stock Aluminum tanks in 3 days, and it's a beautiful tank. It's not epoxy coated, but I can Awlgrip it if I want. I Awlgripped a custom tank I had built for my Sailboat, and after 13 years it looked as good as the day I painted it. The company is Boyd Welding, 352-447-2405, and they're in Ocala Florida. They have a selection of stock tanks, and also build custom tanks.

Wow! That's several great choices I did not know about 9 years ago. Almost makes me want to cut out my front tank and drop in a replacement. Almost, that is.

Ok, so with some further thought I think I may have come up with a solution, since we'll have the bracket, the entire transom will be closed off, and so would it be acceptable to run the fill lines and vent lines straight aft with a filler cap at the stern? This would keep all of the lines straight and we'd only need to cut a notch in the top of each frame. Also, regarding the frames, to fit the dimensions of our tank (roughly 73" long) do we move the centre sections of the frames back from the rest of the sides to fit the tank like framing a window?

Would running the fuel lines straight back be an issue? Also with an aluminum tank, any suggestions on keeping it free of moisture/corrosion?

Sorry to be impatient, but winter is fast approaching, and we need an answer to our questions as soon as possible, it's been almost a week since I asked a question that could have major implications to the fuel system and I need an answer, is there any problem with routing fill, air, and engine lines straight back through the frames with a filler cap on the transom instead of trying to bend them through the stringers and up a frame. We want to get our framing done before winter, and this is really holding us up, so Jacques, an answer in under a week would be much appreciated as time is a factor.
Sorry about the rant.
Liam.

I need an answer, is there any problem with routing fill, air, and engine lines straight back through the frames with a filler cap on the transom instead of trying to bend them through the stringers and up a frame.

None at all that I know of, unless there is a boat specific problem. Sounds like a good clean way to do it.

Also with an aluminum tank, any suggestions on keeping it free of moisture/corrosion?

Not a big problem. The more full you keep it, the less condensation you will get, but the biggest thing is to use non-ethanol fuel if you can get it, and use a fuel stabilizer religiously. And a good fuel filter/water separator.

I answered at the start of the thread and did not add anything because what others have written is correct.
The routing of the harness and the fuel lines can be done anyway you want, under the gunwale is fine but keep in mind how things will bend when you tilt the engine.
The steering cables are another matter. You can't go straight through the middle. How are you going to connect to the steering tube unless you come from the side?
Maybe I misunderstood the question.

I did not see this as a design question. Builders like to discuss options about cables, vents, tanks etc.

Hello Jacques, sorry for the grumpiness yesterday, I was just getting anxious about the winter coming, I just wanted to verify that it is ok to route the fuel lines straight back since that would involve cutting a notch in the centre sections of the frames. We'll route the steering cables and probably electrics under the gunwales for simplicity. Also, looking at the plans, to fit our fuel tank which is 73" long, should we move the centre section of frame D aft as needed to fit the tank? My final question is about frame E, since we'll have a bracket instead of a motorwell, Should I move frame E to the very back leaving the motorwell sides 4" long from the stern, and make another station to go where frame E is shown originally on the plans?

Do not cut a notch in the center section of the frames. Drill a hole as close to the center of the frame as possible and run your tubes through which your fuel line will run. A notch in the frames will weaken them.

Another station where E was is fine, it will give you more room in back, just remember the rule to leave at least 3" at all points. I'm not sure where your measuring your 4" at if you could clarify that it may or may not be okay.

Hi Tom, thanks for the reply, I would measure the 4" from the bottom of the transom, so the motorwell sides would only be 4" wide at the base, if 3" works I'd do that instead, also would you suggest any other bracing to strengthen the transom for the bracket?

Hello all, as things begin to thaw here in Canada, we've begun planning our next steps of construction. Going back to our fuel tank woes, I was wondering if instead of going for a belly tank, it would be reasonable to put in two 27 gallon tanks on either side of the hull, built into seat boxes sitting on the sole, just aft of where our pilothouse door will be located. Would this setup cause any weight and balance issues/ can we leave the space where a belly tank would have been as storage for things like waterskis etc? I checked with my local marine mechanic, and he said there would be no issues with plumbing etc, there would just be a T valve for the two tanks before the engine, much like the fuel system of high wing Cessna aircraft. I really like the idea of having an easily accessible plastic tank instead of a hard to get at aluminum tank in the center. The tank I'm looking at is a moeller tank, the dimensions are 27" long by 21" wide by 12" high.

Hi guy yeah spring is slowly coming. As to the fuel tanks as I recall the P19 as well as the C19 are designed for 2 40 gallon tanks in the center section. Of course you can change that. I would never go with tanks on either side of the hull do to changes in weight as they are emptied.

On another point there is no reason to beef up the transom for a bracket. It is plenty strong enough as is. If you want to do anything put a clamping board where the bracket will attach, 3/4" would be fine. As far as moving Frame E back towards the Transom you will need to keep it about 10" from the transom and all the bracing in place. You can put some storage hatches in it.

Hi Tom, the issue Im having with the center tanks is just that I can't seem to find any plastic tanks that would fit, most aluminum places either quoted really high (one in Canada said $2200 for a 50g tank), or would involve me waiting for quite a while for the tank to be made then shipped. I also really don't like the idea of a metal tank that could corrode. Correct me if I'm wrong, but with a tank on either side, wouldn't the fuel pump draw an even amount from each thus maintaining equilibrium? As for the C of G change, I was thinking of placing a fresh water tank in the center to balance it all out again.

On another note, we ended up deciding not to do the bracket, I want to get the build done and keep it simple. It is also very pricey especially with the exchange rate. It would cost us pretty much an extra $3000CAD to have it built, shipped and installed.

Have you tried these folks? speedytanks.com Everyone here uses them. They coat there tanks included in the price. Design it to your dimensions and put the fittings where you want them. Give them a call and see what they can do for you.

No the pick-ups will not draw evenly from each tank do to the rolling and motion of the boat. You will need to switch from tank to tank. If you put trim tabs on they can be used to offset the draw down of the fuel tanks. No need for water in the keel it will just reduce performance, 20 gallons is 200lbs that the motor has to push.

TomW1 wrote: ↑Mon Mar 13, 2017 8:39 pm
No the pick-ups will not draw evenly from each tank do to the rolling and motion of the boat. You will need to switch from tank to tank.

Last time I checked, a fuel tank pickup was on the bottom of the tank.
Does a motor quit burning fuel when you encounter a wave or go around a corner?
An incorrect post like the quote above is the reason to look to experienced boat builder's for advice.
Where is Cracker when you need him

I just ordered a 60 gallon belly tank from SpeedyTanks. The tank was just over $600. It will end up a little higher because I got all the fittings and fuel gauge and sender from them. As for shipping it is hard to believe it will be higher than mine. Shipping was $430. I have not received the tank yet so I can not say how it looks but many folks here have been pleased with them.
There is one good thing about wing tanks in that they add to initial stability by having the weight further out . I thought long and hard about plastic wing tanks but in the end I decided it was simpler to go with the belly tank.

Hi Fuzz, thanks for the reply! I really am leaning towards the wing tanks just for their simplicity. I like the durability/ peace of mind of the plastic, and the ease of inspection/ if I ever need to remove one. I also work a summer job at a boat shop so I can get the moeller tanks for manufacturers price... I was gonna build seatboxes anyways, and the stability would seem nice. The redundancy of having separate tanks also appeals to me ( if one got contaminated you could run the other etc). And I can then mount my fuel system at the end once the boat's on a trailer when I can take it to my mechanic. Just thought I'd check if there were any major design/ structural hiccups this would cause.

Ps. the belly space could then be used as a storage locker for water skis etc!

This is the great thing about custom building your own boat. You get to do it the way you want it

As long as you don't foam in an aluminum tank and have it epoxy coated it would probably out last you.
I think i paid about 550 for my 50 gal tank from Speedytanks a few years back.

Aripeka Angler wrote: ↑Mon Mar 13, 2017 9:30 pm

TomW1 wrote: ↑Mon Mar 13, 2017 8:39 pm
No the pick-ups will not draw evenly from each tank do to the rolling and motion of the boat. You will need to switch from tank to tank.

Last time I checked, a fuel tank pickup was on the bottom of the tank.
Does a motor quit burning fuel when you encounter a wave or go around a corner?
An incorrect post like the quote above is the reason to look to experienced boat builder's for advice.
Where is Cracker when you need him

Richard meant to leave that out and I guess I didn't. Of course the pickups are at the bottoms of the tanks. Man I miss Larry.

grundasaurus wrote: ↑Tue Mar 14, 2017 2:48 am Hi Fuzz, thanks for the reply! I really am leaning towards the wing tanks just for their simplicity. I like the durability/ peace of mind of the plastic, and the ease of inspection/ if I ever need to remove one. I also work a summer job at a boat shop so I can get the moeller tanks for manufacturers price... I was gonna build seatboxes anyways, and the stability would seem nice. The redundancy of having separate tanks also appeals to me ( if one got contaminated you could run the other etc). And I can then mount my fuel system at the end once the boat's on a trailer when I can take it to my mechanic. Just thought I'd check if there were any major design/ structural hiccups this would cause.

Ps. the belly space could then be used as a storage locker for water skis etc!

You make some excellent points, but remember that by going with wing tanks you give up stability by not having the fuel low and in the center of your boat. You also incur extra expense with dual fuel lines, gages, wiring, etc.

And as Fuzz said the nice thing about building one of these boats is you can build it the ways you want to. So build on and enjoy the experience

What bracket did you decide to go with/