Fitting 20-inch-shaft Engine to older 13-footer

[Ocean31]

I have a 1972 13-footer that needs a "newer" engine. I have been looking for a Yamaha 30-HP two-stroke-power-cycle engine. Almost every engine offered out there is a 20-inch-shaft model. My 13-footer needs a 15-inch-shaft engine.

[How can a 20-inch-shaft] engine [be fitted on a] 13-footer [that needs a 15-inch-shaft engine]?

[Phil T]

The subject of older 13-footers needing a 15-inch-shaft engine has been discussed countless times.

If you do not select a short shaft (15-inch) then a long shaft (20-inch) will require you either install a bracket or install an insert to fill in the notch.

There are several options, including:

Transom Riser
https://www.nausetmarine.com/shop/boston-whaler-transom-riser/
https://www.kentfabrications.com/transdaptors

Engine Bracket
https://thmarinesupplies.com/collections/boat-performance/products/hi-jacker-fixed-jack-plate-4-inch

Setback Bracket
https://thmarinesupplies.com/collections/boat-performance/products/mini-jacker-jack-plate

[jimh]

A c.1972 13-footer with a notched transom designed for a 15-inch-shaft outboard must be one of the last ones made with that configuration. As noted, there are not many modern outboard engines at the 30-HP power level available with a 15-inch-shaft.

In addition to the mechanical bolt-on devices that Phil mentions, another option is to re-work the transom to a 20-inch-height and eliminate the notch. An earlier discussion in this same forum demonstrates a very nice modification to a 13-footer to raise the transom. See

20 inch shaft on a Classic 13
http://continuouswave.com/forum/viewtopic.php?f=6&t=64

Also, for an example of a mechanical solution, read

Cetacea Page 56
http://continuouswave.com/whaler/cetacea/cetaceaPage56.html

[jimh]

If you do not wish to rework the transom in some manner, I believe that Tohatsu makes a few engines with 15-inch-shaft length.

The Tohatsu model MFS25 is a tiller-steered four-stroke-power-cycle engine available in a 15-inch-shaft length. That engine would solve your problem. See

https://www.tohatsu.com/outboards/25_4st.html

[biggiefl]

I believe you can not get PTnT with a 15" shaft. Many people put 20inch engines on their older hulls, as Phil and Jim mention. Many people want and desire an electric start engine with power trim and tilt engine, and it will benefit in resale. And, as you know, will be much easier to find used or new.

[jimh]

NICK--I think a pull-start engine on a 13-footer, particularly with tiller steering, is a good fit. Having to manually start an outboard engine gives the owner an incentive to keep the engine in proper tune and use good fuel and oil.

[biggiefl]

With a tiller I totally agree. When you have to stand up, turn around, climb over the seat, battery & gas tanks to pull start the engine is not convenient, especially if you waterski.