Thinking about a custom belly fuel tank

[chille51]

Hey all - I am thinking seriously about having a custom belly tank fabricated for my 17' Arima Sea Ranger. There is some precedent for this down in the states, and some build threads on the Arima forums. The idea is to repurpose the existing in floor fish box, which I don't really use for anything other than random storage. The benefits I am looking for are improved ride/handling - which by all accounts this mod achieves since these boats are quite butt heavy and mine is no exception - with two batteries, 23 gallon factory tank, main motor and kicker all contributing to stern weight. I am also thinking ahead to repower time and the likely step up from my existing 75hp to a 90hp, and the extra weight that may bring. The other benefit is that it gives much better access to the bilge, which is a real PITA to get at right now with the bilge hoses and pumps under the factory tank, and only a small access hole in the fish box to work with.

I've already been researching potential welding/fab shops here on the Island that can do this work, and have some feelers out to get an idea of price. So not really asking for suggestions on where to get the work done, though I would definitely take any advice on that too. My real question here is more about a sober second thought before I commit. Any gotchas or things I should make sure we take into consideration in the design? If anyone can point me to the appropriate sections of the TC regs that would be applicable to fuel tanks, that would be helpful. I always seem to get lost trying to read those. I am aware the fittings need to be on top of the tank, but beyond that not sure. Are there testing requirements I need to make sure the shop can do? Just trying to do my research and solicit the advice of those that may be more experienced in such things. I don't want to just be 100% reliant on what the fabricator tells me.

Any words of advice appreciated. I'm pretty much decided to go ahead with this project - just trying to make sure I have the knowledge to get it done properly and safely.

Here are a couple examples from the Arima forums that are the main inspiration. These guys are both down in the states though, so looking to make sure I am aware of any regs that are specific to Canada.

https://www.arimaowners.com/index.php?topic=10279.0
https://www.arimaowners.com/index.php?topic=18964.0

 

[salmonkiller01]

Testing of the tank and or certification would be a concern. If something happens what will insurance say. Moeller makes plastic tanks in all sizes and shapes. Not sure if plastic or aluminum is better

 

[CIVANO]

5 pages on arima site

Custom Belly Tank

Custom Belly Tank

arimaowners.com

 

[chille51]

5 pages on arima site

Custom Belly Tank

Custom Belly Tank

arimaowners.com

Yep, that's where I got the ideq from

 

[chille51]

Testing of the tank and or certification would be a concern. If something happens what will insurance say. Moeller makes plastic tanks in all sizes and shapes. Not sure if plastic or aluminum is better

Yes, that is one of the questions I will be asking. On the Arima site there was a couple guys that went the Moeller route but to make it fit they had to modify the tanks, moving connections - thus voiding any certification it had.

 

[Eden Island]

Hey all - I am thinking seriously about having a custom belly tank fabricated for my 17' Arima Sea Ranger. There is some precedent for this down in the states, and some build threads on the Arima forums. The idea is to repurpose the existing in floor fish box, which I don't really use for anything other than random storage. The benefits I am looking for are improved ride/handling - which by all accounts this mod achieves since these boats are quite butt heavy and mine is no exception - with two batteries, 23 gallon factory tank, main motor and kicker all contributing to stern weight. I am also thinking ahead to repower time and the likely step up from my existing 75hp to a 90hp, and the extra weight that may bring. The other benefit is that it gives much better access to the bilge, which is a real PITA to get at right now with the bilge hoses and pumps under the factory tank, and only a small access hole in the fish box to work with.

I've already been researching potential welding/fab shops here on the Island that can do this work, and have some feelers out to get an idea of price. So not really asking for suggestions on where to get the work done, though I would definitely take any advice on that too. My real question here is more about a sober second thought before I commit. Any gotchas or things I should make sure we take into consideration in the design? If anyone can point me to the appropriate sections of the TC regs that would be applicable to fuel tanks, that would be helpful. I always seem to get lost trying to read those. I am aware the fittings need to be on top of the tank, but beyond that not sure. Are there testing requirements I need to make sure the shop can do? Just trying to do my research and solicit the advice of those that may be more experienced in such things. I don't want to just be 100% reliant on what the fabricator tells me.

Any words of advice appreciated. I'm pretty much decided to go ahead with this project - just trying to make sure I have the knowledge to get it done properly and safely.

Here are a couple examples from the Arima forums that are the main inspiration. These guys are both down in the states though, so looking to make sure I am aware of any regs that are specific to Canada.

https://www.arimaowners.com/index.php?topic=10279.0
https://www.arimaowners.com/index.php?topic=18964.0

If you wanted advice from a professional who isn't the one trying to tell you something, you might talk to a company like Blackline. When they rebuilt my Hourston, they had a custom belly tank fabricated to replace the original, which was corroded. They subcontracted the work.

 

[Fishalot]

I have had a few Arimas. If you go to a 90 it will likely be same weight as the 75 as usually same block. Trim tabs would be a significant improvement in ride quality and you likely will want some regardless of belly tank or not. The tank idea is good however expensive and filling the tank and venting properly is a concern. The hold is great for fish storage and misc items. You could add trim tabs then decide if more mods are necessary.

 

[chille51]

I have had a few Arimas. If you go to a 90 it will likely be same weight as the 75 as usually same block. Trim tabs would be a significant improvement in ride quality and you likely will want some regardless of belly tank or not. The tank idea is good however expensive and filling the tank and venting properly is a concern. The hold is great for fish storage and misc items. You could add trim tabs then decide if more mods are necessary.

Yes, trim tabs are probably in the future too. I am leaning towards the belly tank first because I'm quite butt heavy even at rest, which the trim tabs won't help with. Plus, I want to do some rerouting and replacement of my bilge hoses and to do that the factory tank has to come out anyway. Figure if I go to the belly tank now I can maintain that bilge access permanently, not have to worry so much about damaging the factory tank getting it out or putting it back in.

 

[kaelc]

New power and custom tank will run you into the cost of a 2 footitus upgrade but might not add a ton of resale value? Might be cheaper to buy a bigger boat better balanced with newer power and sell yours as is?

I just got a quote on a new on sale 150hp and it was 27k installed, 90 would be cheaper but could cost close to 20k installed with taxes?

Not sure what a new tank would cost but if you have to cut and reglass the floor 10k would be cheap.

 

[salmonkiller01]

27k for a 150 installed? New everything for that?

 

[DuroBoat]

Just gotta say, imo Arima 17 is one of the best, if not the best, 17’ ocean boats out there. Worth customizing I had a Arima 19 hardtop sea ranger so I’m bias but I’ve owned a lot of boats. The 19’ always felt stern heavy too - especially with a lot of gear loaded near the stern.

 

[chille51]

Just gotta say, imo Arima 17 is one of the best, if not the best, 17’ ocean boats out there. Worth customizing I had a Arima 19 hardtop sea ranger so I’m bias but I’ve owned a lot of boats. The 19’ always felt stern heavy too - especially with a lot of gear loaded near the stern.

Yeah, I love the boat and am prepared to sink a little cash into it to make it mine

 

[chille51]

New power and custom tank will run you into the cost of a 2 footitus upgrade but might not add a ton of resale value? Might be cheaper to buy a bigger boat better balanced with newer power and sell yours as is?

I just got a quote on a new on sale 150hp and it was 27k installed, 90 would be cheaper but could cost close to 20k installed with taxes?

Not sure what a new tank would cost but if you have to cut and reglass the floor 10k would be cheap.

I get where you are coming from and I do have similar thoughts myself on occassion. A couple things though - 1) I do really like this boat and think its worth putting some love (love = $) into to make it mine. 2) This is definitely the biggest boat I can park on my current property. It just fits in my boat shed, which I can just back the trailer up my driveway with the clearances I have. Anything bigger and I need moorage or a different house with a flatter lot. This isn't my forever boat but its probably my next 10 years boat.

My gut instinct, no research budget for this project was $3K. I have two ballparks from two different fab shops, both in the $1500-$2000 for the tank range. I can go smaller and try to fit it in the existing fish box (ie no glass work) - or just cut out the bottom of the box. The Arima heads consensus seems to be that the fish box is not structural. But if anyone with more experience than me in the Nanaimo area wants to come by for a homebrew or two and talk it through I'm game for that. I think I can handle the plumbing myself.

Repower is a whole other discussion - maybe look at lease returns in a year or two.

 

[Sr SQ]

I just did one for the boat Im building but its small, only 135l
TC has lots of specific things pertaining to wall thickness, baffling and fill/vent size that I can't remember off hand however I know one of my factory boats didn't follow all the regs.
Any reputable shop will do you right, your pricing seems to be in the ballpark.
I had CJM cut and bend the pieces (3/16") and welded it up myself, tested it @ 2.5-3psi leak test for 24hrs for my own warm and fuzzy
I was shocked at the price of the proper rated hose for the fill and venting!!!!!!
If I remember right it shouldn't be part of the structural integrity of the hull?

 

[Fritz]

Hey all - I am thinking seriously about having a custom belly tank fabricated for my 17' Arima Sea Ranger. There is some precedent for this down in the states, and some build threads on the Arima forums. The idea is to repurpose the existing in floor fish box, which I don't really use for anything other than random storage. The benefits I am looking for are improved ride/handling - which by all accounts this mod achieves since these boats are quite butt heavy and mine is no exception - with two batteries, 23 gallon factory tank, main motor and kicker all contributing to stern weight. I am also thinking ahead to repower time and the likely step up from my existing 75hp to a 90hp, and the extra weight that may bring. The other benefit is that it gives much better access to the bilge, which is a real PITA to get at right now with the bilge hoses and pumps under the factory tank, and only a small access hole in the fish box to work with.

I've already been researching potential welding/fab shops here on the Island that can do this work, and have some feelers out to get an idea of price. So not really asking for suggestions on where to get the work done, though I would definitely take any advice on that too. My real question here is more about a sober second thought before I commit. Any gotchas or things I should make sure we take into consideration in the design? If anyone can point me to the appropriate sections of the TC regs that would be applicable to fuel tanks, that would be helpful. I always seem to get lost trying to read those. I am aware the fittings need to be on top of the tank, but beyond that not sure. Are there testing requirements I need to make sure the shop can do? Just trying to do my research and solicit the advice of those that may be more experienced in such things. I don't want to just be 100% reliant on what the fabricator tells me.

Any words of advice appreciated. I'm pretty much decided to go ahead with this project - just trying to make sure I have the knowledge to get it done properly and safely.

Here are a couple examples from the Arima forums that are the main inspiration. These guys are both down in the states though, so looking to make sure I am aware of any regs that are specific to Canada.

https://www.arimaowners.com/index.php?topic=10279.0
https://www.arimaowners.com/index.php?topic=18964.0

I made new tanks for my boat and phoned TC and they directed me to a document.

The document you seek is TP 1332 which is a free PDF on the TC website.

When I told my surveyor I made new tanks his eyes rolled but when I showed him the receipts for the material, the pictures and that the tanks met the requirements including thickness, labeling, pressure testing, bonding etc. he was happy. My boat is insured and the details about the tanks were on the survey report.

Hope this helps

 

[chille51]

I made new tanks for my boat and phoned TC and they directed me to a document.

The document you seek is TP 1332 which is a free PDF on the TC website.

When I told my surveyor I made new tanks his eyes rolled but when I showed him the receipts for the material, the pictures and that the tanks met the requirements including thickness, labeling, pressure testing, bonding etc. he was happy. My boat is insured and the details about the tanks were on the survey report.

Hope this helps

Awesome, thanks! I will be checking that out for sure. Most of these fab shops I have talked to didn't sound like it was their first time doing this, and that it was fairly routine for them. I'll be asking them some questions about these requirements to get a feel for how well they know them before I commit to anything.

When it comes to insurance, I also wonder what the company would say about my factory tank that is 25 years old at this point. I guess I could find a place to test that tank and document it if I decide to not go ahead with this project.

 

[salmonkiller01]

I take it your tank currently is in the back of the boat. Can you not get a belly tank with fill, breather lines and suction to engine in the rear so you do not need to have a modified one made? You may need a deck plate for fuel sender

 

[Brando]

Don’t go less than 3/16”. Use 5052 it forms really well. double clamp your fill. Use marine rated fuel hose not the thinner automotive stuff. Aluminum fittings/valves/barbs only especially under the floor (no dissimilar metals) . Access to shut off at the tank. ensure tank is tested to 3psi soap all the welds etc for leak check. strap/fasten tank properly avoid foam that can trap water against the aluminum. Reference abyc h24 and transport Canada regs available online google them.

 

[noluck]

Don’t go less than 3/16”. Use 5052 it forms really well. double clamp your fill. Use marine rated fuel hose not the thinner automotive stuff. Aluminum fittings/valves/barbs only especially under the floor (no dissimilar metals) . Access to shut off at the tank. ensure tank is tested to 3psi soap all the welds etc for leak check. strap/fasten tank properly avoid foam that can trap water against the aluminum. Reference abyc h24 and transport Canada regs available online google them.

and don't forget to run a bonding wire tab on the tank

 

[BC Coast Pilot]

There's cheaper ways to accomplish what you want. Consider the formula which is weight x distance. you could use 100 kilos of fuel and move it 1 meter (the effect or moment having a value of 100)
Now think about moving 2 batteries at 75 kilos but move them 4 meters (up to the bow maybe) the moment (75x4) would have a value of 300. effectively having 3 times the value in a shift of a lesser weight but a further distance. Adding weight may not be the best solution, but consider shifting existing weight to accomplish what you need. If you are bent on adding weight, try throwing the equivalent (lead?)of the tank you suggests weight (full of fuel) in the locker and see how she rides