I am in the process of building a small longtail and have two options on the drive shaft housing. I can go with a 1.5" diameter tube with .188" (3/16") side walls. That tube 53" long will weigh 11.5 lbs, empty. The other option I have is a tube that is 1.25" in diameter with .065" (1/16") side walls. That tube will weigh in about 4 lbs, empty. If anyone has any insight into which one will work best, please let me know.

Engine: 6.5hp
Boat: 1232 jon
Riding conditions: open water, shallow water with sandy and muddy bottoms w/ occasional submerged log.

Thanks

i would go with somethin aroun .125", biggers always stronger so if .188 is the only other option id go with that. i would wanna make it a longer shaft though. the longer the shaft, the more forward thrust you get. longatials rely mostly on forward thrust, as oppsed to upward.
weight is a major factor,and the /065 could work and might be alright in open water, but when you get to jackin that shaft around in the mud and got the shaft inside spinning at 3000rpm, that .065 housing can seem a little on the thin side, which is why i would go with .125 or bigger

hope that helped

It did. Since I don't have any experience with LT's, I wasn't aware of the forward thrust vs upwards thrust. Thank you!

no problem bud.
i do wanna tell u that now that u have recieved information you are required to keep pictures and updates of your build posted on this forum. thanks

A 1.250 O.D. with a .188 Wall is a common size of either steel or aluminum, and is generally available from the tubing people. I sleeve either one to make a carrier for the seals.

Mark F. Cheney

The pipe you are considering sounds a bit on the heavy side. The Thai 6.5 hp longtails use a galvanized steel pipe with a 2mm wall thickness, which is plenty thick. The Thai's have been making longtails for over 50 years, and they know what they are doing. Hope this info helps.