transom question

[allanbroach170]

I just got done replaceing my transom and gunnell wood on my old boat, which turned out well. However my old transom was cut down at one time so a short shaft could be used. That was fine but when you back off the gas you get like 2 or 3 gallons of backwash in the boat so I restored to original height, figuring to now get a longshaft. Heres the problem, my transom is now 24 ins. Which seems to be the same length as a longshaft. What the hell? what size motor do I need?

 

[Frank Acampora]

Re: transom question

15 inches is short shaft, 20 inches is long shaft, and 25 (24) is extra long shaft.

You don't say the year, size, and type of hull but as far as I know, extra long shaft engines are a relatively recent development, say mid 90s. They were made to reduce the following sea backwash that you are describing.

You need to decide whether to use a 25 inch shaft engine or install a transom bracket or jackplate and use a 20 inch engine.

 

[allanbroach170]

Re: transom question

The boat is a 1957 15 foot fiberglass seaking boat so it not a recent development. I don't want a transom bracket cause I want more than a 15 hp motor I don't know what a jack plte is how does that work?

 

[Solittle]

Re: transom question

You could post a picture here & that would help you to get more meaningful responses. From what little you have said my guess is to get the engine you want and cut the transom if necessary to fit. Do a search on jack plate to get educated on that. It allows you to vary the engine height but in your case would probably cost more than would make sense for your rig.

 

[5150abf]

Re: transom question

Since you have the transom built up now start looking for an engine and just make the transom match the engine you find.

 

[freddyray21]

Re: transom question

my guess is your boat had a 24 inch transom and the middle was cut down to 20" when it was new. It would have more than likely had a splash well to catch the water and send it out a scupper. Hard to tell what those boats have had done to them over the years, but they did not to my knowledge have a motor of much hp over a 20" in those years.

 

[tashasdaddy]

Re: transom question

agree with freddyray21. to keep the back wash from coming over the transom slow down slower.

 

[tmcalavy]

Re: transom question

Are you measuring your transom depth on an angle, along the transom angle, or straight down from top of transom to bottom of the boat (keel)? Correct way is to measure the straight drop...have someone hold a long straightedge up against the bottom of the boat so it sticks out past the transom, then measure from top of the transom to that straightedge. My old Texas Maid (1962-63) came with a 20-inch transom. When I mounted two standard leg OMC outboards on it, they were too shallow. Had to lengthen both shafts/legs to put them deep enough so the props would bite. Of course these are older motors with the water pump higher in the leg than newer outboards, so I have to run them a little deeper. Measure the straight drop on your transom and see what length you come up with...the cavitation/anti-ventilation plate on the outboard (horizontal plate above the prop) should be even with the bottom of the boat, or thereabouts...1-2 inches either way. Post back and let us know what you find. Transoms can be cut, but that can alter/ruin the lines of the boat if you are interested in retaining its classic lines.

 

[allanbroach170]

Re: transom question

Are you measuring your transom depth on an angle, along the transom angle, or straight down from top of transom to bottom of the boat (keel)? Correct way is to measure the straight drop...have someone hold a long straightedge up against the bottom of the boat so it sticks out past the transom, then measure from top of the transom to that straightedge. My old Texas Maid (1962-63) came with a 20-inch transom. When I mounted two standard leg OMC outboards on it, they were too shallow. Had to lengthen both shafts/legs to put them deep enough so the props would bite. Of course these are older motors with the water pump higher in the leg than newer outboards, so I have to run them a little deeper. Measure the straight drop on your transom and see what length you come up with...the cavitation/anti-ventilation plate on the outboard (horizontal plate above the prop) should be even with the bottom of the boat, or thereabouts...1-2 inches either way. Post back and let us know what you find. Transoms can be cut, but that can alter/ruin the lines of the boat if you are interested in retaining its classic lines.

I did like you said useing a straight edge it measures 21 now instead of 24, I feel I could use my power plane to take a inch off the top without hurting much. That whould make it 20in - long shaft . I have this old e 10 hp evenrude never used don't know much about it but I measured it and I come up with 18 in. from whare it sit on the transom and the cavitation plate. If short is 15in and long is 20 in what is up with that? Is it a long or a short?

 

[grego]

Re: transom question

Seems a lot of trouble and cash when all you needed to do is, As you back off thottle, make a slow to medium turn,left or right. That should take care of any water coming over transom.