Long Shaft motor on cut transom for 15" motor shaft?

Question

I have to put a 30hp long shaft(20") on my 1960 something Whaler. It has the cut transom for a 15" shaft. I was wondering if this will make my whaler run not normal (porpoising, planing slow).

Answer 1

Jack plate....too much transom stress.

Answer 2

it will NOT work the motor hanging too low(gearcase height) will cause the boat to operate slow and sluggish even if you get the boat up to speed it will cause a VERY large rooster tail like spray. I have seen this bad enough to fill the boat so quickly with water that the person had to STOP to prevent capsizeing! if you operate real slow(trolling speed) it will work but once you try to accelerate the problems will be quite evident. some times the prop will even ventilate so bad(suck air) that it just revs up and looses forward momentim. the added drag at the rear of the boat will also cause severe planeing problems. I have worked at a commercial operation for years and saw people try this several times a week(also putting short shaft on 20 in transom). it DOESNT WORK ps it also stresses the transom as the long shaft will try to torque the transom!

Answer 3

Yes,I have had the same problem as you.

I had a 15" trandom on my catamaran an I have a 20'shaft on my evinride...I went an talked to the local boat shop.

They said if I mounted it an ran the engine i'd kill the engine an my boat that way basically.

SO he brought me over to this wall with all these jack plates.

i ended up getting a $200 *MANUAL* jack plate.

if you get electric jackplates they weight alittle more but it's up to you.

SO getting a jackplate is the solution.

plus it give s you alittle more distance from the transom to the engine so you will alsoget little more performance out of it =]

Answer 4

Get a jack plate or another engine>