Outboard size for old wooden boat question

[ShoestringMariner]

Hey all, I've bought a late 50's built Glen L Zip model. I can choose a classic 50's outboard anywhere from 18 to 40hp to go with it. I cannot recall what the motor rating says on the tag. The seller suggests an 18 hp which sounds like a good choice for my use (pleasure cruising and fishing) but I am concerned it will be under powered overall or "underwhelming" should I want to get out of the weather or zip around (pun intended). This boat being 60 years old, and the transom being only about 3/4" thick (except for the motor plate) concerns me. It looks like its in great shape and seaworthy...but I also don't want to hang a 35 hp on it and have that tear off on me.

Any thoughts form you classic boat guys/Glen L builders?

Thanks in advance!!

 

[DeepCMark58A]

Any pictures of the boat?

 

[Ned L]

Any pictures of the boat?

Yep,... this. ..., We would need to see pictures in order to make any reasonable comment. Not just pictures of the boat, also pictures of the inside of the transom to see how it was put together.

 

[Scott Danforth]

There is also a formula based on boat length in feet, transom width in feet, and transom height. For maxumum legal allowed outboard. It does not take into consideration the build quality

 

[Woodonglass]

I have the Glen-L plans for the ZIP.Building one is on my Bucket List!!!!

If the boat was built to spec's then it'll run up to a 40 hp motor.

​

Length overall	14'-4"
Beam	5'-9"
Hull depth	27"
Average passengers	2-4
Hull weight (approx.):	375 lbs.
Hull type: Vee bottom hard chine hull developed for sheet plywood planking. Power: Short shaft outboard motor to 40 hp. Long shaft motor can be used if transom modified. Can the hull be extended or shortened? Extend: No. Shorten: Yes, up to 10% by re-spacing the frames from the aft end of the stem to the transom a proportional amount. We do not recommend increasing the beam. Trailer: Designed for use with Glen-L Series 1000 boat trailer plans

 

[ShoestringMariner]

Thanks guys. Picked it up this afternoon. Took the 18hp. Can probably go back and get a 25. Hull plate says 25 hp
here's some pics. She's just plain jane, but I think there's promise. Still feel the transom is too light for much bigger

 

[ShoestringMariner]

No Title

Here's some more pics

 

[Woodonglass]

Yeah that's the modified transom for motors up to 25 hp. Plans call for double thickness of 3/4" plywood for motors above 25hp. . It'll be fine for that 18hp but if you want to go bigger I'd add the recommended 2nd layer of plywood.

 

[ShoestringMariner]

Yeah that's the modified transom for motors up to 25 hp. Plans call for double thickness of 3/4" plywood for motors above 25hp. . It'll be fine for that 18hp but if you want to go bigger I'd add the recommended 2nd layer of plywood.

Thanks. Due to its age, would putting a 25 on it be a bit foolish?

 

[Woodonglass]

As long as the wood is in good shape and there's no sign of delamination I'm going to say it would be fine. Raise the 18 up and bounce on the leg. Check the transom for flex. If it has none then a 25 won't be a problem

 

[ShoestringMariner]

As long as the wood is in good shape and there's no sign of delamination I'm going to say it would be fine. Raise the 18 up and bounce on the leg. Check the transom for flex. If it has none then a 25 won't be a problem

thanks..bounce on the leg? I dont know that term

 

[Woodonglass]

That's what we call the Tail piece from the top of the motor to the propellor. Also, most people just use AC Exterior Grade Plywood.

 

[Ned L]

Yep,... "leg" = "lower unit".
For a 25 hp I would also like to see a good size knee between the transom and the keelson / keel batten.

(I also commented over on the WBF about the steering, check it out).

 

[ShoestringMariner]

Thanks guys.

Ned L I like the knee idea. Any thoughts on size? I know you're a wood boat guy, is your preference for a knee in this type of boat wood, or steel/aluminum?