fuel tanks on marine trader 40'

[paulga]

per the youtuber, cutting the hull would save 100 hours labor.
so the marginal benefit depends on how one values the hull integrity, the boat's usage for pleasure, commercial/charter. If I do it, I would pay for the premium to preserve. the best way is to work on it myself, also getting those extensive add-on projects done together..

I watched them open up the hull of a vintage 1980’s trawler (Marine Trader?) and replace diesel tanks last summer. I really wish I had taken pictures and documented the process. They made it look easy. Very little disruption of the interior and engine room. They cut out a panel on each side of the hull, removed the tanks, install new tanks, and re glassed in the panels. The tank work is easily a DIY project if you have a good glass guy to open and close the “wound” on each side.

 

[Cigatoo]

per the youtuber, cutting the hull would save 100 hours labor.
so the marginal benefit depends on how one values the hull integrity, the boat's usage for pleasure, commercial/charter. If I do it, I would pay for the premium to preserve. the best way is to work on it myself, also getting those extensive add-on projects done together.

As far as hull integrity is concerned, I didn’t catch the actual re glassing. My arm chair engineering would dictate grinding out and feathering just like you would a thru hull. Also adding stringers along each side / inside of the hull. My guess is that hull integrity would always be in the back of your mind in rough weather.

 

[Steve DAntonio]

I've encountered this 'cut the boat open' tank replacement approach on several occasions. I would not consider cutting the hull on an FRP vessel to replace a tank, and it's very possible the insurer would disapprove as well. That sort of surgery represents a very large secondary bond, which almost certainly isn't as strong as the original laminate.

More on secondary bonds here https://stevedmarineconsulting.com/fiberglass-repair-and-secondary-repairs-steering-you-straight/

If you were to access the tank for cleaning I'd do it from the engine room, you'd need to remove the equipment from the bulkhead, and the bulkhead, but that's very doable. Then, you could install inspection plates, fairly straightforward, I've done it. Far better than cutting up the cabin sole.

I really hate it when builders cover up tanks, it may look prettier, but I'd rather see the tank, to me that's beautiful.

Fuel tank installations https://stevedmarineconsulting.com/fuel-tank-installation/ and design https://stevedmarineconsulting.com/wp-content/uploads/2022/11/FuelTanksPt1-193-FINAL.pdf

Re: the video...
Did he say plastic tanks "rot" or "rock"? Back Cove uses plastic tanks. I'd prefer FRP, but they do work and I have seen no failures. Plastic has advantages over steel and aluminum, however, custom shapes are not available unless you go welded plastic, and that gets a little iffy.

"Steel is affinity if it's taken care of properly...aluminum is not" Not sure what that means.

"Shelf life on a good quality 500 aluminum tank is 20 years...they have the pores in there..." It's 5000 series, not 500, and aluminum tanks can and do last longer than 20 years, I inspected a 33 year old vessel with aluminum tanks two weeks ago. "Pores" What? "A lot of people think fiberglass is waterproof, it's not it's the gelcoat that's waterproof" Hmm, so why does gelcoated fiberglass suffer from osmosis? He just extolled the virtues of fiberglass tanks, but most fuel tanks are not gelcoated on the interior...so are they not water/fuel proof.

"Half inch thick gelcoat [it's understood he's exaggerating] keeps the moisture out" I've done osmosis repair jobs on many old GBs...so how does he explain that?

This is after just a few minutes of listening, I would not take anything this guy says as gospel.

I've replaced tanks on vessels like this, yes you usually have to cut them up in place and replace with two smaller tanks, but that is doable. $10k sounds cheap even for one tank, but that depends on access, where you have it done and by whom, and will that job and the related work be done competently and in compliance with ABYC Standards, all of which affect cost.

 

[alormaria]

It is a shame my old boatyard is under new management.



It was an everyday occurrence for them to pull an engine, pull the tanks and send them off "intact" to a marine tank welding company who delivered a pair of "cloned" tanks back in 3 weeks. They painted the engine room, replaced all the hoses and the shaft, installed the new tanks and replaced the engine in another week or two. All for a bit less than $8,000.00 in 1995 dollars.



There isn't anyone around here now that can find their ass with both hands. I don't want to go back to 1995 but I sure miss those guys.

 

[fryedaze]

I will buy one of those 1995 tickets [emoji23]

 

[Steve1.0]

Its not rocket surgery. In the OP's photo I see a lectra san system to move, batteries and fuel filters. The opposite side, a water heater and batts. Just focus on one task at a time. It's surprising how quickly each goes.


I pulled the tanks out of my GB 46, one bite at a time. I also replaced the exhaust system and re-plumbed the vacuflush system with pvc pipe where practical, while they were out.


Six tanks, $6500
New risers, $5000ish
New 8" wet exhaust hose $ 100 x ?? (short memory, lousy records)
New 8" FG exhaust pipe, 3 @ 10' $$ (see above)
Sawzalls 2
Blades , lost count.
Time, a few hour at a time when I could. (6 months) while the boat was in the water. Pumping the fuel onboard to the opposite tank and removing 650+ lb steel tank, heeled the boat enough to raise the entire exhaust above the water line, for a less stressful replacement. (but I plugged the transom anyway)


I had to shift the generator from side to side for each.



The width of my new tanks goes like this, 2 aft tanks (port and stb) 17.25" to just fit thru the cabin door. The fwd tank (port & stb.) 15". This was because the last tank in (fwd) had to slide in vertically behind the engine (cat 3208 x 2) and beside the aft water tank/generator mount box thingy. All have the same profile as the original. (saved a slice of the old tank's bottom for dimension)


Old capacity , 350 gal. each
New capacity, 320ish each


It wasn't easy, but the total work done would have been over 100k easily.

 

[koliver]

If ou are still looking at that Marine Trader 40:
I have a C&L 44. whenever I see a similar boat, it usually turns out to be a Marine Trader, so I think they were made within sight of each other. That observation leads....check the floor for a small, 10"x14" hatch under the settee, on one side and against the wall on the other. Below that hatch are all of the tank connections, and the place incoming water will sit, if any leaks down at the diesel fill. You will know right away what condition the top of the tank is in.
Other locations for failure are the seams, as the welds sometimes leak. There, only an actual leak will tell, and it will start very slowly, with only a blush along the path the diesel must take on its way to your bilge.
As for repairs, I had one weld leak that I repaired in 2021. Installing an inspection/access port was part of the cost, at $3500 $Cdn. Check it out at Belzona.com.
At the same time as my own repair, a friend with a 1970s plastic boat spent over the present value of his boat to have a full tank replacement done at a local yard.