Fell into a nice website while looking for a source of 2" wide veneer for you to use on the coaming. Veneer supplies http://www.joewoodworker.com/ and/or www.veneersupplies.com/

This company also has plans for building your own vacuum system for vacuum bagging. Their system uses a venturi "pump" which attaches to a standard air compressor, but has two nice features: A vacuum/pressure switch turns off the airflow to the venturi once you achieve whatever degree of vacuum you wish. If there are any leaks, it does another draw down cycle. With this cycling action you don't have a constant flow of air out of your air compressor, so you don't have the compressor running all the time. Harbor freight has venturi-type vacuum pumps at a reasonable price which I believe can be used for this.

They also make vacuum storage tanks from short lengths of 3" sched 40 or sched 80 PVC pipe. Pre draw a vacuum into the reservoir and attach it to your vacuum bag and it will suck the thing dry in a hurry, and then shut off--unless there are leaks, in which case it will cycle on and off. look for their instructions at:
http://www.veneersupplies.com/pages/DIY__Vacuum__Press.html
and
http://www.joewoodworker.com/veneering/v2-about.htm this one is several pages long. Keep hitting the "next page" arrow at the bottom of the pages.

These people also sell HH-66 glue, which Tom Yost has popularized with his PVC skinned boats. Of course their take on it is that the stuff is great for making vacuum bags.

But back to your problem--here is one source for vaneer for your coaming.

Have fun

PGJ