I noticed in one of your pics you seem to be using a small "flapper" type check on your transom drain... I thought, wow, neat idea! So how has it worked out so far? What material did you use for the flapper?

Here's the pic:

Hey Marc
yes ive allways run a drain like this and find it works way better than anything else ive tried
its very cheap and with the drain hole widened if the boat crosses another boats rooster and takes a big drink the boat empties of water in about 2 seconds cause of the venturi effect at speed and when the boat stops the pressure pushes the flap over the hole and makes a seal.
the best material is very thin latex,ive used swimming caps and the bladder out of a football before
Cheers Mark

Cool idea! I might have to give it a try! Thanks for the info.

Could you post some pics of the flap lifted up as well as a closer look of the system you made.... Looks toooo simple.. Just want to make sure I am seeing what I think I see!!! Does that flap go under the boat or stop at the bottom? Just looks too easy.. I guess the old saying KISS IS TRUE!! (Keep it simple stupid).... hahahaha

Hey Roger
yes it is a very simple system,i got the idea off a breast pump when i took it to bits(dont ask)
its just about putting the mounting bracket at the right height so that the latex flap will flex easily but springs back over the hole,its also a good idea to epoxy the inside of the hole so that water doesnt penetrate the transom ply.
heres a couple of pics

This method has been used on sailing boats for years. It is effective & simple, there's no reason it won't work on a model boat. They're called scuppers.

I like it!

Sometimes the simple way is the better way. Very nice idea and easy to do. And I like the idea to use swimming caps.

Neat trick! Does the flap-material need to be fuel-resistant?
No worries that the flap-material will memorise the "open" position?
Very thin mylar (gasket material) will probably work also?

Hey Marc
no i dont reckon it needs to be fuelproof,unless you pour neat gas into the boat alot,and latex doesent get a "memory" so thats why ive found it to be the best material and i think its pretty good with a bit of gas anyway
cheers Mark