brackets and engines

albacore00 · #1 02-22-2006, 01:21 PM

I'll be re-powering this year on my 23 witch has a bracket and full transom. my current outboard has a 25 inch shaft. I'm thinking of going to a 30 inch shaft to raise the engine up farther out of the water. could I raise the bracket and still use a 25 inch shafted outboard? would it find water to grab? perplexed!

Scott · #2 02-22-2006, 02:01 PM

Peter
If you're buying a new motor why would you move the bracket to accommodate a 30" shaft yet go back to a 25" shaft ??

Unless I dont understand your question ?

The bracket should have been mounted such that it would run in the best location for a 25" shaft. Not to low as to create drag, not to high as to lose water flow (for your water pickup and cavitation)
There are old posts that address this ... how fast water rises coming off the hull and the offset used to get the motor mounted properly

I see this as having a 30" transom notch and putting a 25" shaft on it.

I think the offset is something like 1-1.5" higher (engine mounted on a bracket)for every 12" of setback (away from the transom) ??

I'm sure Don (Hermco) can get me straight on this ...

hermco · #3 02-22-2006, 02:11 PM

To use a 30" shaft motor you will have to raise the transom of the existing bracket 5" or get a bracket setup to use a 30" shaft motor. You will bury the motor if you try to use a 30" shaft on 25" setup bracket and won't achieve anything by doing so.

Why are you wanting to go with a 30" shaft? The motor should be well above the water on the bracket if it is mounted correctly.

Briguy · #4 02-22-2006, 02:46 PM

You could also run a 30" motor with a jackplate.

warthog5 · #5 02-22-2006, 02:56 PM

Another thing to consider. If you use the same bracket that is designed for a 25in shaft and you still use that bracket and raise it for a 30in shaft. The boat will settle in the water farther down. So you will have defeted what you set out to do with the 30in shaft.

The reason for this is you will have elevated the tub that add's to the flotation of the boat.
A whole other bracket with a taller tub would be warranted to run a 30in shaft and pick up the flotation so the boat sit's like it does now.

hermco · #6 02-22-2006, 03:24 PM

Jackplate would probably work and be the cheapest option. There is a limit to how far you can set back the motor from the boats transom before you begin to lose effectivness. The addition of a jack plate system would move the motor farther aft. The ideal if you have the $ is to use a twin bracket with a 30" shaft motor for max. flotation.

albacore00 · #7 02-23-2006, 12:50 PM

The boat has a full transom with a bracket. I'll be putting in a new transom this spring and I guess be raising the bracket 5 inches up the transom, 1. to get the powerhead farther from the water and 2. accomodate the lower unit properly in relation to the transom to it still grabs water
and pushes the boat. I think I sort of answered my own question.
thank you.

warthog5 · #8 02-23-2006, 02:42 PM

peter did you understand what I said here?

Quote:

Another thing to consider. If you use the same bracket that is designed for a 25in shaft and you still use that bracket and raise it for a 30in shaft. The boat will settle in the water farther down. So you will have defeted what you set out to do with the 30in shaft.

The reason for this is you will have elevated the tub that add's to the flotation of the boat.
A whole other bracket with a taller tub would be warranted to run a 30in shaft and pick up the flotation so the boat sit's like it does now.