Long Shaft and Short Shaft Question

Hello Everyone,

I am new to the site as a member but have been following the site for a couple years now. I would like to say as a jon boat fisherman this one of the best sites on the net, and I am amazed at some of the things you all are capable doing with these boats. I recently sold my 1436 that i modified with the help of this site and bought an alumacraft 1648 with a 20 inch transom. I will be posting my project on that new boat very soon, but I am wondering if I do not plan of planing my boat with a 9.9 hp, could i get by with a shoft shaft? If I understand correctly, the problem with having a short shaft outboard on long shaft boat is once the boat is on plane. I fish mainly 10 hp lakes and would only use the motor move around those lakes without draining my trolling motor. Finding a short shaft in better condition and price is much easier. Can I settle for a 15 inch shaft outboard?

I believe you already answered your question.
You will be able to idle around but as soon as you try to get up on plan you will cavitate.

I would look for a long shaft. Having a 10hp on that boat at full throttle might tend to starve the motor of water for the impeller. Much better performance would come from a long shaft although I doubt a "on plane" condition will happen with either one.
Tim

Just to add to the mix. I have an Alumacraft 1650MV and a Yamaha 9.9 long shaft. The motor was purchased for two reasons; first, it can be moved by one person and I fish in the winter and store it in the house between trips. Second, I hope to use it as a kicker motor for a larger boat, yet to arrive.

My motor usage rate is at about 300 hours and the boat planes just fine. However, I have a "High Thrust" model and can only speak to the performance on that type of setup.

Reviewing your main question, which seems to pertain to using a short shaft on your 20 inch transom, I say go for it. I fish rock infested rivers and troll small lakes, seldom having a need for WOT, either. Plus, my motor hangs down two inches lower than it should and I have been considering a jack plate to raise it up.

In the final analysis, it's your boat so do whatever you want and have a blast.

Thanks everyone. I think I will just hold off and buy a long shaft 9.9. It will be nice to get the boat as close to planing as possible.