DIY static outboard bracket

[peiserma]

Thanks a bunch, you've given me enough to go on for now. I really appreciate it. I'll see what 1/2" angle costs locally, take some measurements of transom and motor, then sketch up some plans. I will post the sketch for final input and recommendations for the proper height. Will need until next week.

Last question before I hide in the mad scientist cave to sketch up my plans: if i use 3" x 3" angle 1/2" thick, setback will be around 4". Using the 2" setback = 1" of lift rule, that equals 2". So I should plan to raise the motor 3" (recall it is a 20" transom and a 25" motor) in relation to my old one?

[smokeonthewater]

the math here would net you 7" BUT instead of just assuming you need to measure from the keel to the top of the transom and from the anti vent plate on the motor to the bottom of the transom hooks.......
Understand that you will set only your lowest possible height here so build to put the anti vent plate 1" below the expected desired height... in this case since you expect to need it 2" above the keel you would aim for a minimum of 1" above the keel.... Then you can raise the motor one hole at a time till you get the best performance.


example: if your motor shaft is actually 26" and your transom is actually 19 then you would need 9" -1" for a total of 8"

[smokeonthewater]

Honestly I have to admit..... while I can't suggest it to anyone else as it is officially a BAD idea I would probably just run the 150 hp pre made plate.... Jus sayin

[Destroyer]

Originally Posted by smokeonthewater

Honestly I have to admit..... while I can't suggest it to anyone else as it is officially a BAD idea I would probably just run the 150 hp pre made plate.... Jus sayin

X2.... Since most manufacturers build in a certain load above the rated safe load, and if money wasn't all that important, I'd tend to do the same thing. Understand this is NOT a recommendation, just sayin what I would probably do.
Much like me running a 18hp Kicker on an EZ-IN kicker bracket for several years even thought the bracket was only rated for 10hp. But then again, I've never considered myself as the brightest candle in the box... so what the heck do I know....

[tsubaki]

More to look at.
http://www.wholesalemarine.com/th-ma...extension.html

[smokeonthewater]

Originally Posted by tsubaki

More to look at.
http://www.wholesalemarine.com/th-ma...extension.html

You know.... at $143 shipped THIS^ is another good option

If not you could use this design for yours..... only downside is a couple more holes n the transom.

[peiserma]

Originally Posted by smokeonthewater

You know.... at $143 shipped THIS^ is another good option

If not you could use this design for yours..... only downside is a couple more holes n the transom.

I'd use a 1" plate of aluminum! You know, to give myself some margin ... good idea, I'll price that out Friday, too.

[peiserma]

Originally Posted by smokeonthewater

Honestly I have to admit..... while I can't suggest it to anyone else as it is officially a BAD idea I would probably just run the 150 hp pre made plate.... Jus sayin

I understand the sentiment, but I am an (electronics) engineer working in the nuclear power industry. My design comfort level starts in the 30% to 50% margin range, and if I can talk people into a more robust solution, I will. Then I add a backup system. Actually, we like four backup systems for anything really critical.

It may work just fine for a long time. I understand perfectly well that T&H designed in margin, but I could never sleep well at night using something beyond rated capacity. Fukushima got hit by almost 10x worse than it was designed for, which has no bearing on this topic, but it does reinforce the idea that safety can never have enough margin.

While I appreciate the viewpoint, I'd never be comfortable with it

[Destroyer]

Originally Posted by peiserma

I understand the sentiment, but I am an (electronics) engineer working in the nuclear power industry. My design comfort level starts in the 30% to 50% margin range, and if I can talk people into a more robust solution, I will. Then I add a backup system. Actually, we like four backup systems for anything really critical.

It may work just fine for a long time. I understand perfectly well that T&H designed in margin, but I could never sleep well at night using something beyond rated capacity. Fukushima got hit by almost 10x worse than it was designed for, which has no bearing on this topic, but it does reinforce the idea that safety can never have enough margin.

While I appreciate the viewpoint, I'd never be comfortable with it

Hard to disagree with that, especially since I worked as a mechanical engineer/facilities mgr for the company that brought you 3 Mile Island and owns Forked River Nuke Facility. But you have to remember that we're talking compressive strength here, and for 6061 extruded aluminum angle it's 45,000. Since most of your forces are going to be compressive (The engine pushing against the angle which in turn pushes against the stern of the boat) you're going to have to go some to convince me that it's not safe to up the size of the engine. It's a long stretch from a nuke facility to an outboard bracket. Just sayin...

And yes, for the money, I would buy that mechanical jack plate. You can see the quality that went into the design and machining of it. Nicely rounded corners, all edges broken, etc. Def a piece of quality workmanship.

[peiserma]

Got the new-to-me motor on the boat today. Not rigged yet. With the motor in the highest position, I think its pretty close to where it needs to be. Vance customer service answered my question within an hour or so. Actually Mr. Vance did (small shop). I get 1.5" minimum, plus and additional 4" of adjustable "up". So the jack plate will raise the motor between 1.5" and 5.5" I think it will work just fine.

I am ordering the JPL 4300 when they open up tomorrow. Good price, looks like a good product, responsive customer service, made in USA by a small business. They get my money and a plug on this site.

Will post pics when i get it and also when installed on the boat.

Thank you all so much for your replies to my questions.