I ran mine a couple more times today, and found out a couple of interesting things...

The motor coupler set screws are larger than the set screws in the out-drive couplers. I believe the motor coupler set screws are 1/16" (standard), while the out drive set screws are 1.5mm (metric). Not a large difference (1/16" = 1.5875mm), but enough to strip out the larger screw with the 1.5mm wrench if it's very tight. The cheap allen wrench included with the boat is 1.5mm and will likely strip out the motor coupler screws if they are tight.

The stuffing tube has no bushings, the inner diameter of the stuffing tube is almost exactly the same as the shaft's diameter, so there is no free space to be stuffed with grease. I regreased the drive shaft with marine grease, and it kept water out for one run, but after the second run, I was getting a little water spray inside through the stuffing tube. I guess this may be common with RTRs. I'm assuming that stuffing tubes with bearings on the ends probably create much less friction, and are much more water resistant.

One final thing I realized today.... I need to find another place to run my boat. My gun club's pond is quickly getting mucked up with weeds, algae, etc. I'm told in a few more weeks the surface will be totally covered with crap! I'll have to look for an alternative lake or pond... with any luck, I'll be able to run nitro there and I'll get a nitro boat next! Why not... my SW26 will make a very nice electric recovery boat! I've had very good luck with nitro aircraft engines, and moderate luck with nitro car engines... hopefully my luck with nitro boat engines will good as well!

Do nitro boats run car fuel, airplane fuel... or is there a boat fuel too? The nitro fuel I buy locally has about 12% oil in the car fuel, and 18-20% oil in the airplane fuel (most of that oil is synthetic, with only 1-2% being castor). If boats run on airplane fuel, I'm set... got about 24 gallons of 15% nitro airplane fuel right now!