How to mount my jet motor

[sambrent18]

I just bought an 85 evinrude 35 horse jet that I'm going to put on my 14 foot flatbottm jon. My question is how to mount it. The transom on the boat is 15 inches, from the motor mount that sits on the transom to the bottom of the jet intake is 22 1/2 inches. How far does the jet foot need to sit below the boat. I'm going to use aluminum square tubing to build up the transom and aluminum plate to reinforce it and probably add a couple extra knee braces just for support. I've kinda got an idea how I want it I just didn't know how much of the foot needs to be below the boat.

Thanks

 

[Lil' Blue Rude]

You'll need to build your transom up to 22 inches since you have the 15 inch mid. I have a 94 evinrude 40hp jet with a 15 mid on a 22inch transom. The leading edge of the foot should be level with the bottom of the boat. There will be a little bit of room for fine tuning that depends on your set up. You might have to play with the height to get it just right, to low and it catches water and slows itself down and to high and the motor will cavitate. The easiest way I've found is set the motor a little high then run it, if it cavitates or slips a little out of the hole the motor needs to be lowered a little bit. Keep doing this until it stop cavitating out of the hole and that should be about the best height. Atleast this is the method I used when mounting my motor. I slotted the holes in my tilt trim bracket so I would have that fine ajustment. Hope this helps, if you have any more questions feel free to ask.

 

[sambrent18]

Thanks Lil' Blue
You wouldn't happen to have any pics of your setup you could post would ya.
I was planning on making it pretty rigid with a square tubing frame then putting 1/8 inch sheet over that. I wasn't really thinking of having to adjust it which shows you how much I know. I was gonna beef up the corners like you see on alwelds and blazers because a buddy of mine just about lost the whole back end of his boat just from trailering it back and forth for so long. All the jarring of bumps and potholes broke the welds on his transom.

Oh yeah, trying to figure the best way to build the thing and still be able to mount my trolling motor on the transom too.
Pics of somebody elses setup would help.

Thanks

 

[Lil' Blue Rude]

My boats a 16' 42" blazer ss with long gussets a short single knee brace and an all alumnium transom.m Here's some pics but there not very good ones.
If your beefing up the transom and are planning on adding to the corner gussets they shoulld be extented to your bench if you have one in the back, that adds some more support.

 

[moelkhuntr]

Diamond Tread Aluminum looks nice in the back corners. Like Lil' Blue Rude said, bring the corners up a ways.

 

[fatherfire89]

Ya, like Lil' Blue Rude said. When I mounted my jet motor I had a few 1/8" shims between the motor mounts and the top of the transom. I took 'er out on the river and adjusted the motor height until the motor would only cavitate on really sharp turns. I just bought an Evinrude 35 horse jet I'm going to be mounting on a 14' jon too. Weird. Let me know how it works out and upload some pics if you get a chance. By the way, go to outbaordjets.com and check out their owner's manual if you haven't already. There's some good info on motor height, transom raising/strengthening and all that stuff.

 

[Codeman]

I did a pretty detailed build up on mine here on the forums. I had to rebuild the whole thing but it might give you an idea or 2. Good luck.

https://www.tinboats.net/forum/viewtopic.php?f=3&t=4674