RickK's 170 rebuild

[seabob4]

Scott,
I think we are looking at 2 different things here.  The expansion of any tank is due to the fuel inside of it.  If it can't find a means of "growing" via the sides or the bottom of the tank, it will simply expand towards the area of least resistance, the top of the tank.  It's not like foam expansion, because of it's force and density, to where it WIIL move irresistable forces, i.e. stringers and b/heads.  It's a little bit of expansion in the overall, so I think we are...making a mountain out of a mole hill...  

[dirtwheelsfl]

I agree with gman, a cradle fit to the tank shape and glassed into the notches would be the way id go. I wouldnt bother with the foam, ply with biax on both sides will be strong enough to hold 180+ lbs. 28 gal?   especially tabbed into stringers and bulkheads. I ran a full length of pvc from bulkhead to bulkhead under the tank "floor" in mine. Depending which end your pickup is on, you might consider making one end of the tank floor higher than the other to keep that pickup wet..

[gran398]

Scott,
I think we are looking at 2 different things here.  The expansion of any tank is due to the fuel inside of it.  If it can't find a means of "growing" via the sides or the bottom of the tank, it will simply expand towards the area of least resistance, the top of the tank.  It's not like foam expansion, because of it's force and density, to where it WIIL move irresistable forces, i.e. stringers and b/heads.  It's a little bit of expansion in the overall, so I think we are...making a mountain out of a mole hill...  

Gotcha.

It never hurts to consider "what ifs". We thought we had everything covered....then two weeks later...."Why didn't we think of that?"

[seabob4]

It never hurts to consider "what ifs". We thought we had everything covered....then two weeks later...."Why didn't we think of that?"

Ditto on that...

[RickK]

Moeller recommends 3% room for expansion. Guess I'll tackle that calc when I get there. The bottom of the tank has some round standoffs - I'll get some better pics. I think the suggestions are all spot on, thanks.
I'm connecting stringers together right now and making more.
Another thing to ponder is where to position the tank - the old sat under the console so there was a 16x24 footprint - this has a 28x55 footprint.  I am not adding any setback for the engine so the boat should sit the same.  I have initially set the back of the new tank at where the back of the console started but now I'm thinking I should slide it back a foot.  The hull starts the downward transition into the prow as it goes forward right about where it sits right now - might be easier to make a platform if I slide it aft.

[gman 82 aquasport]

Sliding it back wouldn't be a bad thing, this is what I see , your old tank had a small footprint, weight centered in a 16x24 area, new tank is longer, wider and not as tall, so weight is distributed over a larger area..I would look at placing the tank where I would have a pie hole over the pick-up and it would be under the console.The hose hook-up would have acccess under a pie cover in front of the console, odds are if there is a problem at sometime it will be the pick-up or sender, and it's more protected..plus if you slide it back your notches might not be as much..My tank had a drop to the rear built-in so I didn't have to build it into the floor, so I was lucky

[RickK]

Sliding it back wouldn't be a bad thing, ...I would look at placing the tank where I would have a pie hole over the pick-up and it would be under the console. The hose hook-up would have acccess under a pie cover in front of the console, odds are if there is a problem at sometime it will be the pick-up or sender, and it's more protected..plus if you slide it back your notches might not be as much..My tank had a drop to the rear built-in so I didn't have to build it into the floor, so I was lucky

I put the back of the tank at the back of the console for that very reason but I think I need to figure out a better way and slide it back and have the pie under the helm seat. If I do that I may be able to keep the fill and vent hoses in the console instead of figuring out a way to route them to the side of the boat.
Keep the thinking comin' though...

[Blue Agave]

If I do that I may be able to keep the fill and vent hoses in the console instead of figuring out a way to route them to the side of the boat.

I beleive you will regret putting the fill and vent on the console.

[gman 82 aquasport]

I have to agree with blue agave on this one, I have a tendency to "overfill"  and having gas on my floor isn't my idea of a fun job to clean..Is it possible to run the fill and vent hoses under the floor to the starboard side and then up to the cap and side hull, then make a fglass 3 sided box to cover the hoses, sort of like the older 222's that did not have liners.. just a thought and we all know that can be dangerous

[RickK]

I beleive you will regret putting the fill and vent on the console.

That's where they are now.

The beauty of these small tanks is that when you premix every 12gal = 1 qt of oil.  So I always fill by 6 or 12s - never over fill.
If I was going to run it out to the side of the boat the liner is going to cause some re-routing around the pole storage boxes and such. Maybe I can run it up under the casting deck and out to the side (port) but it would be up around the casting deck.

[gman 82 aquasport]

sounds like a possiblity

[Blue Agave]

That's where they are now.

That's the beauty of a complete rebuild, one can improve on the 35+ year old engineering.  Rick, you're quite the craftsman, I'm sure you will figure something out. Just think, when you pull up to the pump you will not have to climb in & out of the boat to gas up. That only is worth it's weight in gold.

[CLM65]

I don't have a horse in this race, but I have to agree with gman and blue agave.  I think the benefits of adding the fill and vent on the deck will far outweigh the benefits of putting it in the console.  Just my opinion...you're doing a great job BTW.

[gran398]

I'm with the boys.

[Circle Hooked]

I'm with the boys.

Me too, i think the reward in the long run will be worth the trouble now