Installing a motor mount on a Reverse Transom

[stanirish]

Recently got a 30' 1975 C&C 1/2 Ton. It's been neglected for years but has good bones. The diesel engine is a MD2b was rebuilt a few years ago but the owner did not replace the freeze plugs and going some fresh water to salt has caused these plugs to leak. I've decided to remove the diesel engine and mount an outboard; I rarely need this lil monster 23 hp diesel and it's nearly shot and do not want to replace it.
My question concerns the reverse transom:
1) does anyone know what the degree on the transom is, I'm thinking 10 to 15 degrees, and
2) I will need a mounting plate to correct this degree, can someone suggest a product out there, I will likely have to have one made, and
3) if you have any experience doing this on your boat this sailor would appreciate hearing from you. Thanks

[TrentePieds]

Not very difficult to determine, is it:-)?

Hang a 2 foot plumbline off the taffrail. At the end of the plumbline 2 foot down from the taffrail, measure the horizontal distance from the transom to the nether end of the plumbline. Transscribe these two measurement to a piece of paper so they form the sides of a right triangle. Connect the "other" ends of the lines to show the hypotenuse. Lay a two-buck protractor from Staples or some such on the "picture" and you can read the "angle off vertical" directly.

All the best

TrentePieds

[Bowdrie]

You would be amazed at how many things can be accomplished with a "Wixey".
Wixey.com - Digital Angle Gauges

[psk125]

30 feet's method works for a traditional transom, but for a reverse transom it might be easier to lay a straightedge on the deck aft, overhanging the transom and use a bevel gauge to take the angle off. Transfer the angle to a piece of paper and use the protractor on that. Remember that the outboard can also be adjusted to different angles, and that the weight of the outboard (and the operator) hanging off the back end of the boat will cause the angle to change a bit too. Before going to all the trouble, make sure you can find a motor with a long enough drive to keep it in the water when the boat is going into waves.

[Jammer]

TrentePieds, respectfully, you should try to get with the times. (You too psk, we crossposted )


Use a level app on your smartphone. I use Dioptra. There are many others. Some of them are probably better. Then simply hold the smartphone on the transom and read the angle.


Also works a treat for measuring heel.


Stanirish, you can make a shim out of wood. I would use a scrap of oak, mahogany, or teak. Outboards have some angle compensation built into them so that may not be necessary. You will need some sort of mounting bracket regardless of the angle. You might want to consider the pantograph-style aluminum ones that allow you to raise the motor out of the water when sailing or at the dock.

[psk125]

Originally Posted by Jammer

TrentePieds, respectfully, you should try to get with the times. (You too psk, we crossposted )

You're right. I took a sextant and chronometer on our cruise this past season.

[Jammer]

Originally Posted by psk125

You're right. I took a sextant and chronometer on our cruise this past season.

Good for you. I'd like to try that myself.

[stanirish]

TrentePieds,
I used your right triangle method using two levelers one taped horizontally to the stern out over the transom and one held vertically. Took measurements of base and leg of triangle and put on paper to use a protractor. Angle in question turned out to be alittle over 28 degrees. Also backed it up with some trig (inverse sin on iphone x is the 2nd button holding the phone long side horizontally to view expanded calculator etc). Seems about right, thanks.

[stanirish]

Actually I've decided not to replace the diesel; she needs some work and the outboard will be good back up till I get the bugs fixed on the md2b.

[beyopo6206]

Nice ….