1972 Chrysler Charger 118 conversion

[Woodonglass]

Re: 1972 Chrysler Charger 118 conversion

Uhhmmm your Transom was 3" thick??? Never seen one that thick on a boat this size!!!!! Typically they are 1 1/2" thick and you make a new one by gluing two 3/4" pieces together. You might want to study this... "Fabricating Decks, Stringers, and Transoms"

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

Uhhmmm your Transom was 3" thick???

Oh duh :embarassed:

You're right, it was 1.5" thick. But it was 4 layers of plywood (not 6), so must have been 3/8" plywood. Was nice red douglas fir too, the parts that weren't rotten.

But 2 layers of 3/4 was what I did last time, and if the consensus is that's enough, I'm sold.

 

[matt167]

Re: 1972 Chrysler Charger 118 conversion

IMO, get the most plies that you can. If that means 2 thicknesses of 3/4" than do that, but in my case, the supplier from the lumber yard I used had 3/4" that was 5 ply and I got 2 more plies by using 3 layers of 1/2". Tiny bit more work, but I know that it is 2 plies stronger than it could have bee n.

3/4" Arauco is supposed to be 7 plies so if you can get that, get it. Most 3/4" is 5 plies and in my case, 1/2" was 4 ply

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

@matt167

WoG had me sold on 3/4", but I was just drawing it out and I realised that since my transom is 28" high I'm going to need a full sheet for each layer. I don't need 3/4" anywhere else, but I'll need 1/2" to make the stringers and bilge box. 3/4" will leave me a lot of waste, so I may just go with the 3 layers of 1/2" after all. Plus I'll get the extra plies.

Never seen Arauco in these parts, don't know anything about it.

 

[jigngrub]

Re: 1972 Chrysler Charger 118 conversion

Managed to get a 37 gallon aluminium fuel tank for free (just had to remove it from the old boat).

So there goes the latteral support of your 5lb. foam eh?!

Not sure if you realize it, but to be USCG compliant that tank has to be set in it's own watertight compartment below deck to contain any fuel that may leak out if the tank develops a leak. This is usually achieved by setting the tank between 2 full length/height stringers with a bulkhead at each end with stringers and bulkhead completely glassed in making it liquid proof. These compartments are commonly referred to as fuel tank "caskets".

 

[Woodonglass]

Re: 1972 Chrysler Charger 118 conversion

I'm confused, How will you have less waste by using 1/2" plywood.??? I agree with JNG That Tank has NO place in that boat. Even if you cut it down to 20". A 14' boat shouldn't be carrying more than 12 gals of fuel IMHO. You really have to be concious of your weight capacities. It's not that much in a 14 footer.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

So there goes the latteral support of your 5lb. foam eh?!

I mentioned above that this tank will be cut down from the 6' you see there to 20" long. I don't think this will compromise the structure much but perhaps I should consider compensating with some sort of rib fore and aft of the tank.

Not sure if you realize it, but to be USCG compliant that tank has to be set in it's own watertight compartment below deck to contain any fuel that may leak out if the tank develops a leak. This is usually achieved by setting the tank between 2 full length/height stringers with a bulkhead at each end with stringers and bulkhead completely glassed in making it liquid proof. These compartments are commonly referred to as fuel tank "caskets".

I did not know this. My plan was to "float" the tank on the foam... that is, support it a couple inches above the hull on some small blue styrofoam tabs, and let the pour foam encase and support it. US Composites states on their website that "gasoline and acetone will not cause any destruction of this foam" and that 4lb foam is "appropriate for filling around gas tanks" so I took this to mean it wouldn't need to rest in a box.

Looking at the equivalent Canadian regulations I see the directive "polyurethane cellular plastic, which is used to encase metallic fuel tanks, shall have a minimum density of 50 kg/m? (3 lbs/ft?)" which seems consistent with my plans.

Thanks for the heads up... think I'll call Transport Canada this week and confirm.

Incidentally, the boat I took the tank out of had no support at all, that tank was just resting on the hull. Didn't seem like a great idea to me.

 

[matt167]

Re: 1972 Chrysler Charger 118 conversion

Agree. I'd use a 12 gal above deck portable tank. Under the splashwell would be an ideal placement..

As for the plywood, count the plies. You may get more with the 3/4 than 1/2". Depends on the brand. I wouldn't just rely on minimizing waste savings. What I actually did was clamp 3 sheets togther and cut it out in one shot. I actually wasted a TON doing it that way, but I bought accordingly understanding the waste. It was quicker, less chance of getting it wrong and the extra $30ish cost for basically wasting a couple half sheets was worth it just for time savings alone.. Got the transom knees out of those 3 sheets too.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

I'm confused, How will you have less waste by using 1/2" plywood.???

Take a sheet of 4x8 plywood, and cut out a piece 72" by 28". You are left with a piece 20" x 96" (and a bit). If you have no use for this piece because you don't plan to use 3/4" plywood anywhere else in your boat, it's waste.

If, OTOH, you need to frame some boxes with 1/2" plywood, and make a stringer with some long strips of 1/2" plywood, you can now use this leftover piece which means it won't be wasted.

I agree with JNG That Tank has NO place in that boat. Even if you cut it down to 20". A 14' boat shouldn't be carrying more than 12 gals of fuel IMHO. You really have to be concious of your weight capacities. It's not that much in a 14 footer.

If you take a 37 gallon tank that is 72" long, and make it 20" long, it holds 10.28 gallons, which is less than 12 gallons. No one is going to force me to fill that tank, but if I go up north for an extended trip on a remote river system, the extra 30 lbs (5 gallons) of gas will be welcome. Furthermore, I'd prefer to have any extra weight low and in the centre of the boat. Lastly, since I'm moving weight (me) back I need to compensate by moving weight (fuel and batteries) forward.

This boat was 675lbs (presumably w/o motor) new, and had a capacity of nearly 1100lbs. Pretty sure she will be lighter when I'm done, and she will only carry two passengers. I think I have accounted for the weight properly.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

Well, no luck finding anyone at Transport Canada who is of any use.

However, I did find the US regulations here and here which seem to be in line with what Transport Canada says. Specifically:

?183.516 Cellular plastic used to encase fuel tanks.

(a) Cellular plastic used to encase metallic fuel tanks must:
(1) Not change volume by more than five percent or dissolve after being immersed in any of the following liquids for 24 hours at 29 ?C:
(i) Reference fuel B ASTM D 471 (incorporated by reference, see ?183.5).
(ii) No. 2 reference oil of ASTM D 471 (incorporated by reference, see ?183.5).
(iii) Five percent solution of trisodium phosphate in water; and
(2) Not absorb more than 0.12 pound of water per square foot of cut surface, measure under Military Specification MIL P–21929B.
(b) Non-polyurethane cellular plastic used to encase metallic fuel tanks must have a compressive strength of at least 60 pounds per square inch at ten percent deflection measured under ASTM D 1621 (incorporated by reference, see ?183.5), ‘‘Compressive Strength of Rigid Cellular Plastics’’. (c) Polyurethane cellular plastic used to encase metallic fuel tanks must have a density of at least 2.0 pounds per cubic foot, measured under ASTM D 1622 (incorporated by reference, see ?183.5), ‘‘Apparent Density of Rigid Cellular Plastics’’
[CGD 74–209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 77–98, 42 FR 36253, July 14, 1977; CGD 81–092, 48 FR 55737, Dec. 15, 1983

Looks like I'm good to go.

Also found some useful info on this site on how tanks and metallic fills need to be grounded.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

Went out at lunch to find out how much to get the tank cut down... guy wants $225 :grumpy:

Not entirely surprised, but was hoping to get something closer to $100. Going to try a couple smaller places, but most likely I'll end up cutting it and fabricating the end myself, and then getting someone with a TIG welder to do the welding for me.

-edit-

Found a guy who will do it for $100, yay!

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

So last night we hooked up the Chrysler to a gas tank, wired her up, put her in a tub of water, and gave her a go. Started on the second try, as soon as I choked her! Gotta love these old Chryslers. It had sat in a field since 2007, so I wasn't expecting much, but just like the smaller 35hp I have, it was there for me.

Looks like someone has already replaced the fuel lines, which is a bonus. It sprayed water fine, but I'll probably replace the impeller as a matter of maintenance.

 

[jbcurt00]

Re: 1972 Chrysler Charger 118 conversion

It's alive!

Congrats!

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

--- dupe post

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

$120 later I have a new 10 gallon tank :happy:

 

[jigngrub]

Re: 1972 Chrysler Charger 118 conversion

Tank looks good.

Did you have it pressure tested?

You should seriuosly consider cleaning it up with a stainless steel cup brush and painting it if you're going to put it below deck.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

Did you have it pressure tested?

Yes, it was. The guy who did it builds gas tanks... he's semi retired now and runs a small shop as a hobby.

You should seriuosly consider cleaning it up with a stainless steel cup brush and painting it if you're going to put it below deck.

I was going to clean it but hadn't thought about painting it. It's aluminium... do I still need to paint it? Is this to prevent corrosion?

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

So last night after work I discovered that there was a piece of wood under a layer of fiberglass that I had overlooked. The last 5 feet of the keel widens out into a flat triangle about 8" wide at the transom, and there was a triangular piece of plywood on top of it with a layer of mat, and then the stringer. It was soaked through and delaminated, but not rotten.

Anyway, out came the grinder and the chisel and a couple hours later it was gone. Getting very close to done and my grinding and sanding before the transom, stringer, and boxes go in.

 

[jigngrub]

Re: 1972 Chrysler Charger 118 conversion

I was going to clean it but hadn't thought about painting it. It's aluminium... do I still need to paint it? Is this to prevent corrosion?

Yes, galvanic corrosion.

You may want to take a look at the info in this thread:
http://forums.iboats.com/boat-resto...ndings-aluminum-fuel-tank-failure-591458.html

The USGC circular.

 

[Arawak]

Re: 1972 Chrysler Charger 118 conversion

Today I drove to Michigan to get the foam from Michigan Fiberglass. It was supposed to have been at a pickup location in Marine City, just across the river from Canada, but when I got there they had forgotten and I ended up driving almost to Detroit. Irritated, but I got a good price on the foam, a freebie for my trouble, and a lot of advice that I wouldn't have gotten at the depot.

I also took the opportunity to stop in at Tony's Marine Service on Marine City Highway. This guy has a junkyard full of old boats in the back, and a huge barn full of just about any boat part you could imagine. Managed to find a top mount Morse binnacle, a complete steering system with wheel, and the cables for both for not much.