Best outboard motor bracket for transom

Mark Prouty · Post by **Mark Prouty** » Mon Apr 25, 2005 10:32 am

I have a Fulton outboard motor bracket but it only has a vertical lift of 14 inches. I don't feel this is enough to keep my 6hp 4 stroke motor from draging in the water under power. Any Ideas?

Moe · Post by **Moe** » Mon Apr 25, 2005 11:11 am

What is the distance from the highest point inside the transom clamp to the tip of the skeg?

What is the distance from the anti-ventilation plate to the end of the skeg?

--
Moe

Mark Prouty · Post by **Mark Prouty** » Mon Apr 25, 2005 11:19 am

Ok, I got you. I'll do it tonight but why?

Moe · Post by **Moe** » Mon Apr 25, 2005 11:29 am

So I can put it together with this data from Garelick and get a better understanding of the problem.

--
Moe

Mark Prouty · Post by **Mark Prouty** » Mon Apr 25, 2005 1:12 pm

One point to ponder is that the motor on the bracket can't be tilted on the Mac transom.

picture courtesy of Duane Dunn

Moe · Post by **Moe** » Mon Apr 25, 2005 1:15 pm

Noted. Thanks.

--
Moe

mike · Post by **mike** » Mon Apr 25, 2005 1:45 pm

Mark,

You may find that, assuming you want the ability to lower the motor into the water for backup propulsion, a certain amount of dragging while in the up position is inevitable. I spent quite a but of time mounting my bracket (the same as yours, I believe), and after mounting it so that the anti-cavitation plate was approximately even with the bottom of the hull, the skeg of the little motor just barely touches the water when in the up position. Unfortunately, when underway, waves and/or heeling often cause it to drag more.

--Mike

kevin carroll · Post by **kevin carroll** » Mon Apr 25, 2005 5:50 pm

Mark, did you need any backing plates? How did you secure the engine mount to the transom??

Thanks

Kevin Carroll

Mark Prouty · Post by **Mark Prouty** » Mon Apr 25, 2005 6:24 pm

I haven't installed a motor yet but Duane has.

Click here

Mark Prouty · Post by **Mark Prouty** » Mon Apr 25, 2005 6:26 pm

Moe wrote:What is the distance from the highest point inside the transom clamp to the tip of the skeg?

What is the distance from the anti-ventilation plate to the end of the skeg?

--
Moe

Transom clamp - skeg 39"
Plate - sket 18.5 "

Rolf · Post by **Rolf** » Mon Apr 25, 2005 7:29 pm

I've got that same bracket mounted with a backing plate for my 4 horse 4 stroke. If you want it to work properly as a backup motor, high speed dragging is inevitable. Storing it on bracket not a good idea unless motoring slow.
R

Moe · Post by **Moe** » Mon Apr 25, 2005 7:32 pm

Wow... I understand now. My Big Foot 60's AV plate to skeg tip is a bit under 17" for a 14" prop... I was thinking a little kicker's would be a good bit less. I'd want vertical travel 3-4" greater than that distance to get the skeg 1.5-2" out of the water when up and the AV plate (with the water intake just below it) 1.5-2" submerged when down.

--
Moe

Greg · Post by **Greg** » Mon Apr 25, 2005 9:24 pm

Mark,
If the AV plate was at water level, how much would the lower unit clear the water when the motor is tilted? Also, how much room in front of the transom bracket is needed for clearance when the motor is tilted?

Maybe one of the following:

1. Something like the Garelick Fixed-Mount Bracket (small custom bracket-probably deeper than the Garelick) type setup may or may not allow enough clearance to water when tilted.

2. Something like the Garelick Fixed-Mount Bracket (small custom bracket) type setup with the Adjustable bracket bolted to it may allow enough room to tilt the motor after lifting the bracket to full up.

3. An adjustable bracket with longer arms.

Greg

Duane Dunn, Allegro · Mon Apr 25, 2005 10:06 pm

Mark, It sounds to me like you have a long shaft motor. My motor is 29" from the tip of the fin to the inside top of the transom clamp. The cavitation plate is 18" below the line transom clamp. My skeg tip to cavitation plate distance is 11" As far as I know this is considered a standard shaft length motor. Does such a deep shaft work with your dinghy? Seems like it would put the prop very low. Ideally the cavitation plate should line up with the lowest point in the dinghy transom. Mine is a bit below this, your's must be way deeper.

The motor bracket I have is a Sea Fit SFMNT#159. West marine part# 381709. They sell it for $99. It is all nice stainless steel which I like better than the aluminum one I had on my previous boat. It's rated for 100lbs. It has a 14" range of motion.

As I indicated before, originally I made a guess at mounting height with the boat on the trailer in the back yard. I was too low. At the original height the tip of the motor (a 6hp Yamaha) just cleared the water when the boat was not moving, At higher speeds the prop would catch and spin. Because of the clearance to the transom when the motor is in the up position, it could not be tilted up out of the way. It could however be tilted up to the shallow running stop. In this position it only caught the water in the biggest waves. Even at full speed it stayed clear of the wake in flat water. It was perfectly servicable in our 3-1/2 week 500+ mile trip last summer in this low mounting position.

In testing it as the backup propulsion motor I found that the motor head was too low and close to the water in the down position. It needed to come up 4"-6" to be right in the down position. This higher position keeps it well clear in the up position, even in the vertical tilt position. What I did was drill a new set of upper holes and put the lower bolts in what were the upper holes. This raised it 5". In this position it is well clear of the water at all speeds, yet is still at the right depth when lowered as a backup motor. The 14" of travel is more than sufficient. Even more clearance can be gained by tilting up to the shallow running stop, but this isn't necessary any more.

As you can see in this picture the bottom of the bracket is in line with the bottom edge of the transom flange. This is the low original position I mounted it in. Now it is almost a full bracket height higher than shown in the picture. For the same bracket, if I were to mount it again I would place the bottom of the bracket 4" above the line of the transom flange. This is about 1" lower than where I now have it and should be the optimum height. I have mine higher only because it reused two of the original 4 holes. I took the easy way to fill the abandoned lower holes. I just gooped up two short SS bolts and re-attached them in the holes. They are above the water line and sealed up just like they were when they held the bracket.

Mark Prouty · Post by **Mark Prouty** » Tue Apr 26, 2005 5:00 am

Moe wrote:What is the distance from the highest point inside the transom clamp to the tip of the skeg?

What is the distance from the anti-ventilation plate to the end of the skeg?

--
Moe

I measured wrong:

Transom clamp - skeg 27"

Plate - skeg - 9.25"

Thanks for the feedback all!

I'm a motor mounting coward!

MacGregorSailors.com

MacGregorSailors.com

Best outboard motor bracket for transom

Best outboard motor bracket for transom

Backing Plate