Removing aux tank on 1999 268 islander

[efx]

I have a 1999 islander. The 72 gallon aux tank is full of water from previous owner. It’s from 1999. The main tank is 128 gallons and is clean and has no water present. I’m repowerring with 4 strokes twin 150’s. I’m thinking of just removing the aux tank and leaving the cavity clear and maybe use it for a storage space. The 128 gallon will give me at least 200 miles of range. Is there any reason why I should keep the tank?

 

[leeccoll]

I suppose if it were me, answer would be how far offshore I would go and how frequently I go out.

As far as safety, it is always a comfort if you are out there and know you have the extra tank in case there is a remote chance of your main tank being unable to supply fuel to the twin 150's-like a bad anti siphon valve, etc.

I fly a lot (pre Covid that is) and I appreciate modern aircraft are designed with 2 back-up systems in case the primary failed.

 

[efx]

Thanks for the response. I’m thinking of using the storage space which would be freed up by the tank removal to always have a 6 gallon jerry can and an empty 6 gallon portable tank. Just a thought as a back up. I would never need more than 200 miles of range and I can get that with the 128 gallon tank easily. The front 128 gallon tank is in much better shape also since it’s incapsulated within the middle section the deck. With the 150’s I can get 2 mpg at 4000 rpm.

 

[leeccoll]

Of course,
You know your situation best. Some others have converted that space as well.
I have an empty rear coffin on my 228, but never converted.
Could be a good project for ya, if you go forward, keep us updated!
Lee

 

[efx]

Yep. I will keep everyone updated. The space is a waste since I would never carry that much fuel. Here is a photo. That 72 gallon is coming out and then I’ll epoxy paint that space and add a large access panel there.

 

[family affair]

Taking into consideration the fuel efficiency improvements of late model engines compared to what your boat came with, losing that tank and the extra fuel weight probably won't put you too far off from the range your boat had when new.

 

[efx]

I believe you are correct about the original range and the new range with the more efficient engines. And here is the real benefit, islanders are narrow for trailering and unfortunately they put the scuppers below the waterline much easier than sailfish or Marlins. Getting that weight out and having the fuel weight always being more forward will be much better for the hull posture. Deck will drain better, drains and scuppers up higher, I can stand in the back with other guys when fishing and the scuppers will be higher. Plus I have a place to store all the cushions and ditch bag versus cluttering up the cabin. Here is a photo of the inside of the Forward main tank. Second photo is the aux tank with tons of water and debris. It’s being removed.

 

[family affair]

I agree that the GW models with the short hulls perform better with less weight out back. Put 4 200 lb guys near the helm on the Voyager and it devours chop. Move 2 of those guys to the back seat and things get a lot bumpier.

 

[Toothpick 10]

Did you get a price for replacing the smaller tank?

 

[Stephnic]

Where is your Islander located. I have a couple of questions for you about The auxiliary tank.

 

[efx]

Did you get a price for replacing the smaller tank?

No prices yet. I’m not going to replace it. I would rather have the storage space. I don’t need the extra range of the 72 gallons. 128 gallons is enough.

 

[efx]

Where is your Islander located. I have a couple of questions for you about The auxiliary tank.

I’m in Los Angeles. Feel free to ask questions via pm.

 

[efx]

twin 150s installed. Rear gas tank removed.

 

[Hookup1]

I have a 1997 268 Islander with F-150's. I would consider more HP 4-cylinder block motors. I this Yamaha makes a 200.

I wouldn't worry about the aux tank if you don't need the range (block fill at the fill so someone doesn't fill the bilge with fuel) and allow it to go back in for a future owner.

I almost did tank replacements this year but no fuel in compartment so I'll wait. Given the age of my boat they should be done.

 

[Stephnic]

Boat looks good. I put F150’s on my 98 in June the boat runs great. I am getting 44mph wot.

 

[efx]

Aux fuel tank has been removed. I now have plenty of storage and still 200+ miles of range. Notice the sawzall made an appearance! Not an easy task.

 

[efx]

I went with power tech 3 blade ofs3. 15.25 x 16.
I haven’t rigged the engines completely so no testing yet.

 

[efx]

I reused the steering ram but added a new tie bar. Another tough job! I have to replace the end caps and seals because of leaks.

 

[Hookup1]

Are you doing anything with the main tank? Its probably the right time to swap it out. I like the idea of eliminating the aux tank. I usually only put 20 gallons in it in case I do something stupid like running out of fuel on the main. I'm not running that far offshore and all sending units always are working. I think the boat performs best with fuel forward.

I have gone to 4-blade props from www.propgods.com Haven't test yet - February in FL.

If you think cutting a fuel tank out is hard try cutting two 5 3/8" holes in the bow for a thruster!

Yamaha may be producing a 4-cylinder in-line over the F-150. The hull can handle more HP but the weight of the V-6 is too much. Looks like you are on the right track.

 

[Hookup1]

Yep. I will keep everyone updated. The space is a waste since I would never carry that much fuel. Here is a photo. That 72 gallon is coming out and then I’ll epoxy paint that space and add a large access panel there.

Keep in mind that 72 gallon compartment is isolated from the bilge (won't drain) to prevent fuel from leaning into the bilge.