Re: Merc's on tundras
The small hub props work well on bassboats and lighter hulls. They allow exhaust bubles to cushion the thrust which allows the engine RPMs to peak quicker and improve your holeshot. Once on plane, the exhaust is drawn fully thru the hub and you can often feel it hook-up, sorta like kicking into second gear. Larger props achieve the same effect with ventilation holes or slots. Both work about equally well. The small hub props were an early performance trick before vented props came along.
There are also Merc V-6s that have small hub gearcases. They tend to be a tad faster than the large ones because there is less drag. But they are also weaker and you can tear-up the gears without too much provocation. Another advantage of the small hub gearcases is that they can run in shallower water by about 3". But with the durability issue, it's a give-and-take.
Regarding a short or long kicker, the short would probably work. But the prop may not clear the hull line and may not be as efficient due to turbulance of the water filling in behind the transom. The long would extend below the hull farther and push cleaner water. But it depends on the height of the transom where it is mounted and the angle of the bottom of the hull at the stern. You'd have to do some measuring. It often happens that a short it too short and a long is too long. So you have to judge from that.
Another factor would be the water you intend to troll. For lakes, the long might be the better choice. For rivers, I'd tend to go with the short. With the long, you also want to make sure it will tilt out far enough so it doesn't snag the water when you're up on plane with the big motor.
