Greetings

This is my first post to this board. Recently I obtained an Alumacraft 1236 Jon boat with swivel seats at an excellent price. The only outboard I have access to is an old 1.2 HP Aquabug I use on my canoe. Pretty good bet that little engine is not gonna make the grade so I have been shopping.

The boat is rated for 15 HP. I assume that means a two stroke engine as the tables were set up back when two strokes ruled. Taking an average I notice that most 15 HP two strokes weigh around 80 lbs. Looking at the current market the only new two strokes left are Yamahas and they are hard to find. Looking at the current crop of four strokes the contenders seem to be the Tohatsu/Nissian/Mercury line that have a 9.8 hp at 85 lbs for an electric start model (did I mention I wanted electric start?) and the 15 HP Yamaha two stroke if I can find one at 79 lbs that does not have electric start available.

I have always thought that one should get the most powerful engine the boat can handle safely. But I do not want to be dragging the transom inches above the water.

Here is my question (finally);

Do I need to give up the electric start and go with the 15 Hp if I can find one or will the 9.8 do just fine?

To qualify the question I weigh in at 280lbs, my son weighs around 140. So most days it would be 700 lbs of total boat weight with tackle, cooler ect. I had a 5.5 Mud Motor on it for a while and it would make 12 MPH according to the GPS but it was no where near getting up on plane. I do not want to water ski behind this thing but I would like the boat to pull up and run on top.

I found an old rule of thumb that states you need one HP per 50 LB of boat to plane. I also found an boat builders refference that says flat bottom boats would plane well at one HP per 85 LB of boat.

Given differences in boat loading and balance points that means my boat would plane consistently with between 8.5 to 14 HP depending on the formula you apply.

HUMM

Thoughts, questions, comments, real world experiences?

Thanks

I'm certainly no expert on this, but I push a 1436 jon with an old 9.8 mercury (many lakes here are 10hp and under). I weigh about 180 and I've had fishing buddies up to 250 and have had no problems yet. Normal amount of gear. one 12 volt battery, a cooler, tackle bags, etc.

I hope someone more qualified than me can help you with this one...sounds like you've done quite a bit of research on the subject already.

Good Luck!

10 hp is fine for a 1236. I persoNAlly wouldn't go much higher. It may be rated for a 15 but these aren't the most torsionally rigid boats.   Got a pic?

THIS is a post about the refab job I did on my 1964 1242.

Good luck with her.