New Bottom on a Model 5 - transom question

[hcrane]

Having a new bottom put on a 1929 Model 5 - after all these years it's about time. Have noticed that the port side of the transom is deeper that the starboard side - one gentleman who is no longer with us said that was to counteract the torque of the engine. I got that information in 1992 when I re-engined the boat.

The person doing the work now (who has worked on similar 26' footers) thinks that the transom should be the same depth on both sides. The transom planks were not of constant size either - they were tapered to match the difference in depth.

I'm at a loss and any guidance would be greatly appreciated.

[maritimeclassics]

I restored 2 1929 28' triples that had a rise of about 2 to 3 inches at the stern that started about 24 to 18 inches from the transom. One side was not different from the other though. It is definitely built into the 26 and 28 footers but I don't think its for torque as the engines really didn't have that great of torque for that size of boat. I believe it was more for planning to help the ride and maybe to get the nose down. The 24' and the 20' I did did not have this in the bottom. I would pull some measurements at the last 4 or 5 side frames to the the transom from the shear plank to the bottom and draw it out on a piece of paper, then do it to the other side to see if they are different. A boat I did not to long ago was different on both sides, the bottom was off from the factory so they made it up on the top and just cut the frames a bit higher to make the deck even. It was not a Chris Craft

[jim g]

Years ago i was told by George johnson and a couple of other restorers in New Hampshire. That it was done to compensate for the torque of the A-70 and A-120 engines. Those engines had alot of torque and swung a pretty big prop. What I don't know is whether or not chris craft only did it on the hulls that got the A series motors. The museum might have the hull lines which would tell you whats correct.

[maritimeclassics]

From what I read and talked with people George Johnson was an amazing guy and had many of the 26 and 28 foot Chris Crafts go through his hands, I believe he even owned a couple. I wish that I would have been able to meet him.
Here is my theory on the the bottom. I have all of the drawings for the 28' Chris Craft Triple and used then to reconstruct the hull of 3031 and 3042. It does show that there is a rise in the bottom but only by the table of offsets and not on a detailed notation on the plans and when I figured it all out on paper it was the same on both sides. On one of the boats we had the original side planking and you could see in the shape that there was a definite rise to the bottom. So with that we know that the it was built in the bottom and it was not different on each side.
I total believe that the rise only came on the 28 and 26 footers and that was the boats that they had and option of the A70 or later the A120 and also the Kermath engine. The engines weighed about 1600 lbs for the A70 and a little less for the Kermath. The 28 came depending on the engine and model with a 19X22 prop. The 28' boat weighed approximately 4200 lbs. and had 2 40 gallon fuel tanks and the 26' had 2 33 gallon tanks. The tanks in both boat sit on each side of the hull all the way against the transom sitting from bow to stern and not side to side. Both boats had a third cockpit for 2 people and the back of the seat sat almost up against the front of the fuel tanks. So now it's time for some simple math. We'll say he tanks on the 28 were half full and that the fuel is unleaded and weights 5.5 lbs per gallon. That would be 40 gallons at 5.5 equals 220 lbs. Add in the fuel tanks at approximately 40 lbs each and some hardware 20 lbs and you have a total of 320 lbs. Now its a beautiful day and you have 2 average size people ridding in the rear cockpit at 140 lbs each for a total of 600 lbs. I can't even imagine having the fuel tanks full of fuel. So hopefully you see what my theory is, once again it's all about weight. Having the bottom constructed like they did would help the nose of the boat come down for a little better planing (which they never really did) and keep the rear of the boat from dragging with all of the weight. The torque theory just doesn't make enough sense to me because you are not going to twist the boat or make a 4200 lb boat act funny, the rpms are not enough. Now if it was a blown big block maybe. So it's just a thought so what do you think?

[hcrane]

Thanks for the responses guys - has the pleasure of meeting George Johnson many many years ago - My grandfather purchased the Chris in 1964, replacing a 1920 Consolidated launch (see Fairhaven in CUTWATER). and over the following years got to know George. He was always asking about the Chris hoping that we would sell it to him. The boat had a Scripps but when we got it, it had a Chrysler straight 8 of somewhere between 135 and 150hp swinging a 17x12 wheel I think. In 1992 I re engined the boat myself with "help" from George - he had a pair of Crusader Model 350s he got out of a cruiser and we, in our ignorance, decided to save $200 and purchased the left hand rotation engine, swinging a 17x24 prop - had to load the heavy guys on the port side and the light ladies on the starboard side to attempt to maintain an even keel when on plane - George said oh yes, that's why one side is deeper than the other - Had I known we would have spent the extra $200. Decided to keep the single exhaust but had to make it bigger - George said a 4" would work fine - so out I go and get some 4" copper pipe and a hole saw only to discover the 4" is the inside diameter, not the outside - back to the hardware store to get a 4 1/8" hole saw. Boat now is being repowered with a 6.2l Mercruiser with a carb and raw water cooling and a direct drive Velvet (the 350 had a 1.5/1 I think) - so now hopefully the Chris won't heel drastically when accelerating quickly.
Just talked to the restorer today and one side of the bottom is screwed and plugged - took a little longer than planned - keel and one chine were bad and needed 15 new ribs.