raising transom height

[charkbait]

how do you know how high to go, is there a formula like, prop and water intake must be "X" below the bottom of the boat?

I have a great running long shaft and want to bring it up a couple inches.

 

[tmcalavy]

Re: raising transom height

General rule of thumb is the cavitation plate (horizontal plate above the gear case, where you would attach a hydrofoil for instance) should be even with bottom of the boat. Plus or minus an inch in either direction is also acceptable to some folks. That's the baseline, after that you fine tune with prop(s) and tilt/trim.

 

[tashasdaddy]

Re: raising transom height

if you have a longs shaft (20") on a short shaft boat ( 15-16") buy or build a jackplate, i built this one.

 

[5150abf]

Re: raising transom height

That is pretty slick Tashasdaddy, I just love to solve problems like that.
My motto "why buy something when you can make it"
I work in an aluminum weld shop so pretty much anything I can think up I can make.
Just finished making LED lights to light my rod holders and another one to get rid of the lantern on my boat(I night fish).
They work better than a lantern and don't burn any gas which is up to $4.50 for a 1lb cylinder
I have rod holders,lanterns ect on 1'' tubing and have 1 1/8 holders around the boat so no matter what situation you are in the boat will adapt, it's pretty neat.
If you can't build one they have non-powered jack plates in cabelas for not to bad a price, remember, there is an astranomical amount of force on the transom so be cereful what you use.
I would hate to see a post "how do you fish an OB off the bottom of the lake?"

 

[tashasdaddy]

Re: raising transom height

there have been many fished out of the water. mine cost me $50, for the 3/16 aluminum and bending. had the plywood. iboats marine store carrys a lot of jackplates.

 

[charkbait]

Re: raising transom height

is the jackplate a necessity or can I use some angle bolted through the transom and existing wood to create an extended height of about 6".

I guess what I'm asking is "does a jackplate give me anything that merely extending the height and reinforcing with angle steel doesn't?"

This is only for a 9.9hp

 

[stevewolverton]

Re: raising transom height

is the jackplate a necessity or can I use some angle bolted through the transom and existing wood to create an extended height of about 6".

I guess what I'm asking is "does a jackplate give me anything that merely extending the height and reinforcing with angle steel doesn't?"

This is only for a 9.9hp

A jackplate is not a necessity. It will help adjust the motor so that the cavitation plate is level with the bottom of the boat. This will reduce drag because the motor is up where it should be rather than sitting deeper in the water. This also keeps the skeg/prop/etc. higher so less chances of grounding. It reduces spray because the motor isn't dragging as much of the lower unit. Jackplates raise, and most also have a setback that will set the motor away from the transom. Many say this also helps with handling.

The drawbacks are you may need to adjust the steering (unless you have a tiller setup, which is my guess?), and more stress on the transom. There are some really small jackplates available for small motors like yours. I'd look at them first to get some ideas.

I use one on my boat so I can run a 70hp 20" shaft motor on a 15" transom. Love mine!

 

[charkbait]

Re: raising transom height

thanks!

 

[jay.robinson15]

Re: raising transom height

there have been many fished out of the water. mine cost me $50, for the 3/16 aluminum and bending. had the plywood. iboats marine store carrys a lot of jackplates.

Would you say that's a pretty typical price? I am just about to buy a jackplate as well.

 

[Captain Caveman]

Re: raising transom height

My long-shaft motor never worked quite right on my long shaft boat. Water would really spray out of the back like my old 35hp motor was really a hydro plane. For a while I was sticking shims and strips of wood on top of the transom. Of course, then the tightening feet were almost off of the transom. I finally decided that raising the transom by two inches would solve my problem.

I went to an aluminum yard and bought a 2" piece of square tube, and a sheet of 3/4" inch flat aluminum. My buddy has the hook-up at work. He cut the sheets down to about one foot wide by two feet high and welded them to the square tube.

All that I had to do was slip this "sleeve" over the transom. I drilled some holes through the aluminum plates and transom and ran some bolts through to hold the whole deal onto the boat.

It's worked great and my motor runs much, much better. I've attached a picture below:

 

[tashasdaddy]

Re: raising transom height

you just built a transom elevator. http://www.iboats.com/Transom_Eleva...07246606--**********.536879365--view_id.40157

 

[Dovekie]

Re: raising transom height

My long-shaft motor never worked quite right on my long shaft boat. Water would really spray out of the back like my old 35hp motor was really a hydro plane. For a while I was sticking shims and strips of wood on top of the transom. Of course, then the tightening feet were almost off of the transom. I finally decided that raising the transom by two inches would solve my problem.

I went to an aluminum yard and bought a 2" piece of square tube, and a sheet of 3/4" inch flat aluminum. My buddy has the hook-up at work. He cut the sheets down to about one foot wide by two feet high and welded them to the square tube.

All that I had to do was slip this "sleeve" over the transom. I drilled some holes through the aluminum plates and transom and ran some bolts through to hold the whole deal onto the boat.

It's worked great and my motor runs much, much better. I've attached a picture below:

elegant, functional, reversible & cost effective - nice!

 

[Captain Caveman]

Re: raising transom height

Transom elevator...hmmm, I knew that there had to be a fancy name for it. I just called it my metal motor thing.

I'm glad that I built it for $30 of aluminum instead of buying it for $165 online.

 

[thurps]

Re: raising transom height

Really simple. I raised the motor on my 13' Whaler with two pieces of 1/4 x 2 x 4 x 16 aluminum channel. Can't believe how it improved the preformance of the boat.

http://i163.photobucket.com/albums/t308/thurps/boatsnow014.jpg
http://i163.photobucket.com/albums/t308/thurps/boatsnow015.jpg
http://i163.photobucket.com/albums/t308/thurps/boatsnow013.jpg