Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Transom

Posted by jsmoooth25 on 09/01/10 - 1:30 PM
#1

We added a 5" spacer on our 1967 13' classic to accommodate a long shaft motor. I would like to know if you have done this and if so when you measure from the top of your transom to the bottom of the boat what measurement do you come up with? I am getting approx. 23" and want to make sure this will not be a problem. Thanks

Edited by Joe Kriz on 09/01/10 - 1:51 PM

Posted by John Fyke on 09/01/10 - 2:05 PM
#2

My guess is your running a 20" shaft motor. A few inches here or there is normal when measuring the shaft. The cavitation plate should be above the keel though.

Posted by jsmoooth25 on 09/01/10 - 2:12 PM
#3

I am actually measuring the boat from the top of the transom to the bottom of the boat. I am curious what others come up with when they measure from the top of their transom to the bottom of the boat. I continue to read to run a long shaft motor you must add a 5" transadapter. I added a 5" adapter and now I want to see what others come up with on their measurements to make sure I am on the same playing field as everyone else. If I measure the transom with no adapter I am coming up with approx. 17". Thanks

Posted by Joe Kriz on 09/01/10 - 2:26 PM
#4

I guess I am not understanding this totally...

A Standard transom is 17 inches... on a 13' model ?
If you add 5 inches to it, that makes 22 inches...

Not all engines are exactly the same length for long shaft motors.
They all can vary slightly.

You really need to run the boat to see if the engine is too high or too low.
In this case, I would start off by having the engine all the way down.
If you get too much spray from the cavitation plate, then the engine is too low and need to be raised up a hole or maybe two.
Major concern is not to have the engine too high where it can't pump water to cool the engine down.

After the height is adjusted properly, then you should see if the prop is the correct choice.
You can view this thread about prop pitch and RPM's on the tachometer.
http://www.whalercentral.com/forum/vi...;pid=67402
and this one:
http://www.whalercentral.com/forum/vi...post_67250

Basically the cavitation plate should be about 3/4 of an inch to 1 1/2 inches above the bottom of the keel.
Again, not too high or the engine water pump won't pick up the water to cool the engine and could cause major damage.
Too low, and your performance suffers.

Edited by Joe Kriz on 09/01/10 - 2:27 PM

Posted by jsmoooth25 on 09/01/10 - 3:01 PM
#5

Thanks for the responses.

Posted by todd12 on 09/01/10 - 7:07 PM
#6

If you measure flat agaist the transom, you should get 21.5 to 22 inches ( follow transom angle ). My adapter plate is set for 22 inches and I could of went higher by looking at my cavitation plate. This info was provided to me by another member here. He actually provided a photo with drawings. Maybe he will see this and reply. Good luck !

Posted by CES on 09/02/10 - 10:40 AM
#7

You'd most certainly have to take a few test runs once you install your motor. Ideally, while on a plane, you'd want to see the top of your cavitation plate above the water. If you cannot see the cavitation plate and there's an excessive amount of spray, you've probably got your motor mounted too low. It's a trial and error type deal at this point.