Long or short???

[knehdn]

I have a 16' open 3 seater Starcraft that had a '61 40 hp Johnson short shaft motor on it. I recently picked up a '64 long shaft, same make and power. Any pros and cons as to which motor would be best suited? I've attached a photo of the boat for clarification. The helm has been removed, as has the transom.
Please and thank you.

 

[Woodonglass]

Re: Long or short???

Welcome to iBoats!
The transom on that boat is designed for Short Shaft Motors.
sinse you have the transom removed, you could quite possibly extended the transom to accomodate the long shaft motor. It has been done before.

I'm just sayin...

 

[knehdn]

Re: Long or short???

Hmmm... never thought of making a new transom. But with a higher transom, wouldn't that increase the torque on the entire transom? Or would a higher transom decrease the aforementioned torque? The original one is in great shape, no punky wood anywhere (photo shown is after several coats of spar varnish). I pulled it in order to 1) paint the boat, and 2) to check its condition. I'll see which motor ends up being the best runner and go from there.
Thanks.

 

[jimdd810]

Re: Long or short???

A 40hp sounds a little big for that boat. Its basiclly the same boat i have only 14ft. Mine is rated for 18hp. I would double make sure to read the coast guard plate for that boat to make sure that motor is ok to begin with. In wisconsin they will tow you to shore and not let you operate that boat untill it is right and also give you a ticket. I could be wrong.

 

[knehdn]

Re: Long or short???

Thanks for your concern, but the compliance plate states maximum 40 hp. It's how I bought it and that's how the previous owner has been running it for the last 30 years or so. They sold it to me cuz they were getting on in years and bought themselves a small pontoon boat to access their island cottage. There was another thread which had a link to the formula for calculating the max hp for a boat. If I remember correctly; you took the length, width, transom height and mutiply that by a set factor; and when I used the formula and it came out 40 hp. I'll search around, and if I can find it, I'll let you see it.
Your 14' boat, is it a Starcraft? If so which model? Please and thank you.

Back to the long shaft motor... what harm could there be by using it, other than increasing my draft?

 

[knehdn]

Re: Long or short???

Found it.
Try to cut and paste this link. I tried it. It works, just erase everything in the address box. Powering is the first section.


http://files.dnr.state.mn.us/education_safety/safety/boatwater/backyardboatbuilders.pdf

 

[Triton II]

Re: Long or short???

Is it possible to swap lower legs? If so I'd chose the best powerhead and fit the short shaft leg to keep the transom as is. Contrary to the above, 40hp on a 16ft open tinny is pretty normal 'round here, but check the capacity label... just in case I'm wrong - it has been known!

TII

 

[Triton II]

Re: Long or short???

Back to the long shaft motor... what harm could there be by using it, other than increasing my draft?

Oops, you guys got in first so yep, use the 40. However putting a long shaft on a short shaft transom will lower the prop by five inches and the result will be an increase in drag resulting in a slower boat with worse fuel consumption.

TII

 

[knehdn]

Re: Long or short???

More drag and more fuel consumption... thanks Triton, those points never occured to me. I guess I'll work on the short shaft unit and keep the long shaft in storage. At least I won't have to worry about the transom and such. And it'll be kinda nice having an extra motor kicking around (seeing as it only cost me 60 bucks).
So with that said, this'll be end for this thread.
Thanks folks.

 

[ezmobee]

Re: Long or short???

You could go this route if you didn't want to raise the transom. http://forums.iboats.com/showthread.php?t=321432

 

[Woodonglass]

Re: Long or short???

Nice one EZ!! I was just thinkin since he had the transom out, Making a new Raised one would not be that big of a deal. Something kinda like this.

It only has to go UP 5" so it could easily handle the torque. 1 1/2" of Laminated plywood can handle quite a load.

I'm just sayin...
http://forums.iboats.com/attachment.php?attachmentid=65169&d=1282657835

 

[knehdn]

Re: Long or short???

Well, thanks again. I'd have no problem making another transom, but that homemade jackplate seems more versatile. You know, in case the long shaft gives up the ghost or vice-versa, I'd just need to install or remove that jackplate and not the whole transom. And it seems that 3/16 aluminum should do it. Great, cuz I'll be getting some for the new helm and the downrigger brackets.

 

[Woodonglass]

Re: Long or short???

Jack plates are KOOL. Piece of advice. Drill you mounting hole over size, fill em with epoxy then re-drill em, that way NO WATER can ever get in the holes.

I'm just sayin...

 

[knehdn]

Re: Long or short???

More great advice. Thank you ... so wonderful how it just never ends.