How deep should the prop be located on a pontoon boat.?

I've been to three dealers %26amp; a repair shop, guess what 4 different answers. By how deep I mean where should the prop be in relation to the waterline on the pontoons. I'm talking a 17 ft Sylvan with a 40 Horse Merc. Thx in advance %26amp; I'm giving a thumbs down to the jughead who tells me it should be under the water!!!How deep should the prop be located on a pontoon boat.?
Since a pontoon boat does not need to plane,prop depth is not really important.I have been rigging boats for more than 35 years and I have just mounted the engine on its lowest setting.Also you won't need to Trim the engine during operation,just insure that you can tilt the engine when you are in shallow water.

Hope this helps.

Good luck and happy boating
The top of the prop should be about 6 inches under the waterHow deep should the prop be located on a pontoon boat.?
Winnie has it right.. a short, concise and absolutely correct answer!!
Well is the water you will be on shallow?? or deep enough to have a long shaft--if the shallow water hits the prop--it's good bye pin and your day is ruined. If the motor is heavy--go for the short shaft--it will PLANE better and the nose won't come up.How deep should the prop be located on a pontoon boat.?
3 feet.
be sure the cavitation plate is below water surface. this insures proper flow of water for cooling and prop propulsion.