home made jackplate

[Canuk]

hey guys, i'm thinking of making a jackplate for a 16x48 modified V jon boat and 25hp honda as I want to run a little safer in skinny water.

I would like to get it as close as I can to start, so any advice on how much i should/can go up and back?

Who has experience with these?

thanks for the advice/comments.

[EZM]

Originally Posted by Canuk

hey guys, i'm thinking of making a jackplate for a 16x48 modified V jon boat and 25hp honda as I want to run a little safer in skinny water.

I would like to get it as close as I can to start, so any advice on how much i should/can go up and back?

Who has experience with these?

thanks for the advice/comments.

Conventionally Mounted - If the prop is, for example 11" in diameter, you will need the full radius of the prop below the boat.

For best performance (for a conventional prop set up) they are a few inches lower yet. Keep in mind you will loose thrust if the water flow is impeded by the draft of the hull. If you dont follow this rule - this creates cavitation.

The further away from the transom you are - the higher up you can come, but if you had a 6" jack plate (away from the boat) - you can gain 2"-3" (in height) or so.

40% is the rule of thumb.

Lots of good articles on the net - have a look.....

[EZM]

Should say one more thing - if you go further back (away) from transom - the load on your transom increases.

With Jon boats the transom may not be designed to put that much strain on it.

I would fabricate an simple and easy jack plate using channel and plate - probably for under $100 and a few hours in the shop. 6" out - 3" up.

If you need to come up 5" or so - you will to come back 8" or so - I'd suggest having a longer (deeper) mating surface to run further down the transom to distribute the load on your transom.

[Shmag]

I agree with EZM, lots of info on the net. I think the one i read up on was on tinboats.net and iboats. If you end up making one post some pics, i am in the market for one as well. Good luck

[Canuk]

Thanks guys, I appreciate the advice. I'm pretty sure I've read the articles on both tinboat and iboat. Some good step by step instructions too.

was just looking for some advice to reinforce what I 'think' I have figured out and also some personal experience which is aways valuable.

Yes, I think the transom on my boat (haven't bought it yet) isn't as strong as the one I sold so that's a good point about more bracing. Originally I was thinking 8" angle on the transom bolted to 12" angle for the motor to mount to.

On the Net there is lots of talk about the cavitation plate, and starting with it level with the bottom of the boat, or maybe 1" higher. I guess that's pretty much in line with having the full diameter of the prop under water (when mounted close to the transom).

Nothing beats experimenting I guess. I'll surely cut slots so I can fine tune the heights and use a back boards of difference thicknesses (or not) to vary the setback.

I making my own stuff, just hope my motor doesn't end up at the bottom of the lake.

Lastly, does anyone know where I might buy aluminum angle (or channel) in edmonton?