Azek Spacers Under Motor Mounts?

[John, CD28]

In order to meet the prop shaft, I need to raise my new diesel about 1.5" I've heard of people using aluminum plate, oak, bubble gum etc. What about a synthetic building product like Azek? It's used as trim boards on houses, and comes in lengths like standard boards. I've got lots of left over bits around the house, some 1" thick. It seems hard enough and rot resistant. It's not as expensive as Starboard, and feels lighter and harder.

Any experience or thoughts on using Azek around the boat? As motor mount shims?

Best,
John

[Figment]

The little bits may feel harder, but the stuff is actually rather supple and wiggly. Much more so than cedar, for example. I don't have any hard data, but I wouldn't expect it to have much compressive strength.

After paying all that money for a new motor, I don't see much benefit to pinching pennies on the shims.

[Tim]

I'd suggest fiberglass, metal, or hardwood.

[John, CD28]

Metal? Hardwood? Everybody uses that. Where's your sense of engineering adventure? I'm going with the Azek. Now, I just need to get some Gorilla Glue to hold them down.

(just kidding)

John :)

[Quetzalsailor]

Azek is cellular PVC. That is, it's slightly foamed to save on the cost (and weight) of the PVC. PVC will creep under load and heat, and is variously brittle, depending upon formulation. I specified it for use on a very large porch, southern exposure, on a local yacht club. It mills well (beads and moldings), handles well, looks pretty darned good. Disadvantages are that you have to paint it anyway and the thermal expansion/contraction is excessive, particularly along its length (wood does not so much along the grain).

I would not hesitate to use it where I did not have to worry about creep, did not need much strength, did not care about the weight. I would not use it under a hot, greasy, vibrating object that I would wish to stay where I put it.

[John, CD28]

Ok,

I cut a small piece of 1" thick Azek, and drilled a 3/8" hole through it. I put a 3/8-16 bolt through the Azek, a set of washers, & a nut, and torqed down. The Azek looked & felt pretty good at 60° (F). Even with a good amount of torque the Azek compressed very little and felt pretty solid. I measured the distance between the two washers as 1.008".

Here's where it all went to hell. I plunked the Azek/bolt assembly into a sauce pan and boiled it for 20 minutes. The wife loves when I do stuff like that. I reached in to lift it out with a tong, and notice the TONG left divets in the Azek at 212°. There was no need to measure between the washers again. I put a socket and wrench on the nut/bolt, and gave it a spin.

The Azek compressed like a marshmallow at 212°. It looks like a good idea in the shop, but this is NOT something you want supporting your hot engine on a warm summer day.

Lesson learned,
John