long shaft Chysler on bass boat

[conor1366]

this is adding on to my Prop question thread but new problem

I am told that the cavitation plate on my motor should be about even with the bottom of the hull. the origional motor for my 1988 15' Bayliner bass boat was a 50 hp Force. The motor it was swapped out with is a 1975 Chrysler 45hp using the same transom mount.

Can anyone tell me if there is a difference in the shaft length from the origional 50 hp Force motor and my 1975 455HH Chrysler?

I only have about 2" I can move it up on the transom.

any ideas?

 

[JB]

Re: long shaft Chysler on bass boat

Either engine came with either a 20" or a 25" shaft, conor. Maybe they were the same, maybe different.

When you want to add to a thread, add to that thread, don't start a new one.

 

[conor1366]

Re: long shaft Chysler on bass boat

sorry. I'm new.

 

[Frank Acampora]

Re: long shaft Chysler on bass boat

Well, Connor First measure the transom from the top of it to the bottom of the VEE or to the keel if it is a flat bottom. Smaller boats like that of that age will never have a 25 inch transom. It will either be close to 15 inches or close to 20 inches--some are 21 for example.

Now, measure the length of the engine midleg from the inside of the clamps to the cavitation plate. It should be 20-21 inches. Some of the old Chryslers had a measurement of 18 inches and these were actually short shaft engines for a 15 inch transom. If a 5 inch extension was added to them to make them long shaft, they would be slightly too long for a 20 inch transom and would need to be raised a bit for best performance.

If it is the case that you need to raise your engine more than the transom will allow, a simple plate made from two pieces of aluminum plate with a 2 x 2 inch piece of wood in between through bolted to the transom will raise the transom enough without doing major damage to the boat. Search the forum for examples--there are several threads with photos.

 

[conor1366]

Re: long shaft Chysler on bass boat

you are right on the money Frank.

transom- 20"

leg to cavitation plate- 25"

material to raise the transom- $20

hours to complete- 5

not knowing what to look for when buying a boat- ignorant



I am thinking about 2 pcs 1/4" thick aluminum and sandwiching the transom with a 2" block in between- I will only need about 5" to raise it up.

the only problem now is on that particular boat is that the transom area is kinda short left to right so they have a "cup" in the side wall to make clearence for the steering linkage..but that is small. no biggie. I can raise it up and create a larger flange plate to cover the hole.


thanks for all your help Frank. This forum in just the last few days I have been apart of it has made me a more informed boater.

thanks again.

 

[eurolarva]

Re: long shaft Chysler on bass boat

Option two is to watch for a 35,45,55 HP lower unit for sale on ebay. The extension plate can come off on your motor. You will however need the drive shaft water tube and shift linkage from the lower unit from ebay. If you use wood to redo your transom do not use pressure treated lumber. The stuff will eat though aluminum. Either use untreated or get lumber from a marina that is still licensed to sell the old pressure treated. Old pressure treated had arsenic in it and it was banned.

 

[JB]

Re: long shaft Chysler on bass boat

I am very shy of homemade transom extenders. I think you would be much better off converting to the 20" shaft. There are also people out there (eBay) who would buy the shaft extender parts to go to 25" from 20".

 

[conor1366]

Re: long shaft Chysler on bass boat

all good ideas I think.

It may be less work to replace with a shorter shaft...instead of drilling a ton of holes in my boat.

thanks for your advice.