speed loss for longshaft motor on short transom?

[tt600]

Through observation and measurement I have come to realize the previous owner placed a longshaft 35 hp johnson on my 16 ft seaking with a short transom. How much speed do you think I am sacrificing with this setup? Is it worth the $120 for an extender? I am thinking if I get 2 mph gain I will do it.

 

[DJ]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

Hmmmm? That is totally up to you. Are you happy with what you have?

Boating is NOT about speed, it's about; "being out there".

To answer your question directly, maybe 3-5 MPH.

 

[sentinel]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

Hmmmm? That is totally up to you. Are you happy with what you have?

Boating is NOT about speed, it's about; "being out there".

To answer your question directly, maybe 3-5 MPH.

I certainly agree with Supreme Mariner!! There is a LOT of excessive drag & turbulance if anything is at or below the chine other than the cavitation plate(fin) which should be level with the chine. Really messes up reaching a plane and likely adds a big bow wave on take off.....

 

[tt600]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

3-5 is definitely worth it on lake powell. I'm going for it.

 

[ezmobee]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

Do it. Long shaft on a short transom is a big drag on performance. Check this thread: http://forums.iboats.com/showthread.php?t=321432

 

[5150abf]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

At least 3-5 possibly quite alot more, that really is alot of extra speed for the cost involved, up and out!

 

[Frank Acampora]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

Not only MPH loss, but impact water may climb the leg and spill into the splashwell at speed. Obviously, this depends upon engine size and boat speed.

 

[tt600]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

just ordered a mini-jacker from basspro. Anyone use one of these? I will post results after the 4th of July.

 

[RZR2007]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

I'd be more pleased with the fuel savings then the 3-5mph, that would just be a bonus!

 

[tt600]

Re: speed loss for longshaft motor on short transon?

Re: speed loss for longshaft motor on short transon?

here is a picture of my transom. I am wondering how much I should lift the motor. Is there a bit of trial and error involved.

 

[tt600]

Re: speed loss for longshaft motor on short transom?

My minijacker came in the mail. I think I will try a two inch lift for now.

 

[nwcove]

Re: speed loss for longshaft motor on short transom?

...........that looks like a shortshaft??

 

[tt600]

Re: speed loss for longshaft motor on short transom?

...........that looks like a shortshaft??

Hmm, must have been measuring the wrong distance before. Now that I measure it the right way I do get 15".

Regardless it still looks like I can raise the engine 2". Hopefully that nets me at least 2mph gain.

 

[srimes]

Re: speed loss for longshaft motor on short transom?

results?

 

[tt600]

Re: speed loss for longshaft motor on short transom?

still sitting in a box in my garage.
My transom is getting a little shaky. Not so sure about drilling holes in it.

 

[tmcalavy]

Re: speed loss for longshaft motor on short transom?

Just from looking at your last photo, I wouldn't mess with it...the cav plate is only about 2-3 inches lower than your keel. If the motor clamps on to the transom, use some shims to raise it up an inch or so...then see if gets you more speed. Probably won't be noticeable.