View Full Version : What plastic for Trolling Motor base ??

07-10-2011, 02:16 PM
My son in law had me mount a electric Trolling motor on his boat using a "one size fits all" factory kit.
The kit has a 1" thick x 4"x6" base that mount to the boat and a 1" thick 8"x10" piece that mount to the electric trolling motor.
The 8x10" has a 4'x6" hole in the center.
The trolling motor is mounted to the boat by setting the trolling motor base onto the boat base and held in place by 2 cross pins.

The bases are made out of some type of black plastic. The plastic is easy to cut and drill and can be scratched with your finger nail.

In order to mount the 4x6" base to the boat,(The base uses 4-1/4" mounting bolts) I used washer to level the base and correct for the boats contours.

What type of plastic would be best to use for a base, that I could machine to fit the boats contours and get rid of stack of washers ?

Thanks for the help.


07-10-2011, 02:25 PM
The best one for that job would be Acetal copolymer. One common brand I use is Quadrant Engineering's "Acetron". Another is Celanese "Celcon". I get mine from McMaster-Carr or MSC Industrial Supply. DuPont "Delrin" would work fine too, though it is a monopolymer.

07-10-2011, 02:30 PM
I just checked the "continuous sunlight rating" on acetron and it gives a 2 which is limited service. I guess that means it's go less than stellar UV resistance. It seemed to say all acetal were the same.
Now if you live in BC it might work since it rains here all the time. ;-)

07-10-2011, 03:21 PM
UHMW would be a nice choice. Very easy to machine, Kinda slipery, low moisture asorbance, its somewhat UV resistant And there are more UV resistant versions. Reasonabley cheap and often found in larger blocks (Someone here has a friggen 4x4 pickup full of the stuff if you can't find someone to sell ya the right sized block without buying a huge sheet)

http://bbs.homeshopmachinist.net/showthread.php?t=9291 <- speaks of the UV resistance of UHMW.

Kinda flows a little, but with good flat washers that should be fine, just make sure to have lots of contact area and tighten it up a few times after the boat makes a few initial runs to compensate for any high spots that flow out.

Other options might include wood (Fiberglass/epoxy coated?)
Aluminum billet mount (Weee)
Steel brackets (Need paint, or stainless, or aluminum) that join to a larger mount plate. (Bolt brackets in place, tack weld to larger plate, Perfect alignment)
Foam coated in fiberglass, Easy to shape, Easyish to make, Very light, very strong.

07-10-2011, 03:30 PM
Similar to fiberglass, G10 would work. It's fairly abrasive to cutting tools though.

07-10-2011, 04:43 PM
I'm not sure where you're talking about, as far as mounting it. I assume it's mounted in the bow area, on the deck, as mine is. That's what I'm picturing anyway.

If it were me, I'd try to find some suitable wood, e.g. teak.

I've had to replace too many little plastic items to have much long term hope for that on a boat.

07-10-2011, 05:40 PM
Yes I am mounting the electric trolling motor on the bow of the boat.
There is no flat spot to mount the base. I used washers as shims to level the base so he could make a test run over the 4th of July weekend.

It worked in that location. I thought I would make a better looking base.


07-10-2011, 06:26 PM
I make marine parts from plastic in my small home shop. I would use either black UHMW or a piece of Seaboard. Where are you located? If you were near me I could tell you where to get a piece. I will look in my shop and see what I have. I do not use 1" but I may have some laying around in my stock pile. Do not use white UHMW if it will be left in the sun it is not UV resistent and will become brittle after a few years. There is a recycle center near me that grinds UHMW & HDPE for re-manufacture and I take my swarf & scrap there the guy lets me dig through the stuff he is about to grind and gives it to me or at least last time he did I am sure if not free it would be very cheap. Before everyone starts making orders for pieces I don't have time to fill orders but if you are near by I will tell you how to contact him.

I am guessing there are not alot of those re-grind businesses because he was telling me that they truck this stuff from all over the country to him. They process it 2 times one time they grind it to .250" chunks and then process it again until it is powder at that point they sell it back to the manufacturer to be melted and formed back into stock. With the price of oil this guy has been making good money.


07-10-2011, 07:13 PM

Mike thanks for the offer. I live in Montana. I guess I should add that to my profile if I can figure how to change that.

07-10-2011, 08:55 PM
I looked in my stock pile I have some grey .750" & black in 1.25" & 1.5" but no 1" material. If I had what you need I would send you a piece on the cheap.


07-10-2011, 09:14 PM
I looked in my stock pile I have some grey .750" & black in 1.25" & 1.5" but no 1" material. If I had what you need I would send you a piece on the cheap.


By the sound of it, he needs to do some contouring and/or use multiple smaller peices as spacers, So he likey will need to machine the thickness to his own specs anyway.