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[sinjon]

The base of the boat is skinned in .9mm ply. The prop shaft comes through at quite a low angle - no chance of fitting a fat healthy block as a base.
My solution is to mount the motor on to a 18mm thick block and epoxy the block at 90 deg. to the hull base,
perhaps some ply fillets to the rear. I have mounted the motor but have yet to 'fix' it in place.
Is there a better way (before I  commit myself)

Colin

Size corrected - Martin.

[Martin (Admin)]

Any chance of a photo?

Martin

[RipSlider]

sorry to be thick:

0.09 or 0.9mm? 0.09mm is thinner than paper.....

However, if it IS 0.09mm, then I can see your problem!

Steve

[andrewh]

sinjon

.09 mm ply is thinner than most paper - the thinnest that I have found is 0.4mm 3-ply which is 16 thou

Pics, Please, as martin says

I'm wondering if you need to mount the motor on the ply bottom, and if it is in a vee, or if there is a frame of formers/longerons that might be a secure base for the mount.

Another thought that might be applicable would be to fit a motor mount plate  - maybe 1/16th ply from side to side and fill under it with expanding foam so it is bonded over a huge area.

However I'm guessing at what the layout might be

andrew

[sinjon]

Sorry misreading my vernier, it is of course 0.9 (not paper!)
I will try to get a photograph - I have never downloaded on Mayhem, but I am aware that there is a mountain of information on how to do so, give me time and I will be back.

Colin

[IainM]

Hi Colin .......  perhaps consider the motor mount shown in the pik attached.



Big advantage is that the mounting plate, the prop shaft and the hull bottom form a triangular shape that is very rigid.
Motor and belt wheels can easily be changed for tuning of prop speed.

Hope this helps,
Iain

[Martin (Admin)]

Photo added to post 4

[sinjon]

Thanks Ian,
That really does look interesting, having trouble with the small print though, but will give it a try this weekend.

Colin

[andrewh]

Colin

Thanks for the picture of the hull - all is much clearer

Iain has pictured a good solution, and I don't for a moment disagree with it
His principle also works for a direct drive motor, too,and the key to is all is to base the motor fixings on the ply bulkheads of your boat

Your pic shows that there are ply bulkheads (ribs) running across the boat at regular intervals
Glueing a ply plate to 2 or three of these and running fore and aft will give a secure base for mounting the motor - if height is a problem you could fix a plate between two of the bulkheads in the motor area so that the ends of the plate glued to the bulkheads/ribs and the plate could nearly (or really) rest on the bottom

This sounds garbled in words - if sketches would help say the word
andrew

[IainM]

Colin, sorry about small print!!
Try http://www.sfmbc.net/prop_motor_mount.pdf for a printable set.

I opted for a ball race on the inboard end of the prop shaft but, since tooth belts don't need much in the way of tension to operate, a plain sintered bronze bush as fitted on the standard prop tube would be OK although it wouldn't last as long.
Would make construction simpler if you don't have access to a lathe.
BTW if you get belt tension on a tooth belt too high, the motor loading goes way up as does the noise - all to no good effect!

Best of luck,
Iain

[DickyD]

You could use one of these.

GRAUPNER COUPLING HOUSING 600 SIZE
Order number 2328
Suitable for mounting of 600 size electric motors onto
6mm Dia stern tubes
. For SPEED 600 – 540 – 545 – 550 Motors

http://www.shgmodels.com/acatalog/