I was under my boat last weekend (Diesel 420 DA) and notice one of the props is loose. Both nuts have backed themselves against the cotter pin. The key is loose too. What is the best way to hold the prop shaft while I torque the nuts again? I intend to take the prop off the inspect key/keyway. I have always been a Bravo outdrive guy…This is my first cruiser.
Tightening Prop
- Thread starter ASH
- Start date
Gofirstclass
Well-Known Member
Is your boat out of the water? That makes it easier. Either way, the nut that's closest to the prop needs to be tightened first. Don't try to lock the shaft in place. Rather, place a piece of 2x2 or similar wood between two of the prop blades and the other end against the strut. That will hold the shaft in place because the prop can't turn on the shaft because it's held in place by the key.
Once the nut closest to the prop is tight, then tighten the other to snug it down.
Once the nut closest to the prop is tight, then tighten the other to snug it down.
I keep it on a lift so it is always out of the water….I will use the board against the strut. I have always had stainless steel props and these seem a little weaker/thinner…I will make sure the board is as close to the hub as I can get it…Thanks!!!!!!!
This is a bit of a debated topic.
Tony at Boat Diesel has the following advice.
http://www.sbmar.com/articles/propeller_installation_big_nut_vs._little_nut/
Tony at Boat Diesel has the following advice.
http://www.sbmar.com/articles/propeller_installation_big_nut_vs._little_nut/
Jimmy Buoy
Well-Known Member
- Dec 3, 2008
- 2,468
- Boat Info
- 2003 Cobalt 293
- Engines
- Twin Volvo-Penta 5.0 270hp & DuoProps
My Prop guy (Prop-Scan Dealer) warns of using a block of wood between the strut and prop blade since it can deform the prop. He says he can often tell which blade was used after completing a computer scan of the prop since it is the only blade out of whack!
I've used a strap wrench secured to the shaft near the exit point from the hull and a 2x4 between the hull and the handle of the wrench. It's a two person job since the shaft needs some constant twist on it to keep the strap wrench tight. The last thing I want to do after spending $800 on having my props trued up is put one of the blades out of whack while reinstalling.
I've used a strap wrench secured to the shaft near the exit point from the hull and a 2x4 between the hull and the handle of the wrench. It's a two person job since the shaft needs some constant twist on it to keep the strap wrench tight. The last thing I want to do after spending $800 on having my props trued up is put one of the blades out of whack while reinstalling.
I've always worried about tweaking the prop...can a strap wrench really hold the 325-350 ft-lbs recommended for the first nut on a 2" shaft?
These props/shafts are super smooth & balanced. I may try that strap idea. I have a chain type visegrip that works like a pipe vise. I am guessing the steel is going to be to hard to get a good bite. I dont want to scar it either. How about a roll pin punch through the cotter pin hole with the jam nut backed against it?
Jimmy Buoy
Well-Known Member
- Dec 3, 2008
- 2,468
- Boat Info
- 2003 Cobalt 293
- Engines
- Twin Volvo-Penta 5.0 270hp & DuoProps
Maybe not, but if its a problem my next step would be using a pipe wrench inside the boat grabbing the coupler. I would not want to put that kind of torque on a single blade for sure!
dpmulvey
Active Member
- Dec 19, 2007
- 4,188
- Boat Info
- 1999/2007 330 Sundancer Hardtop.
- Engines
- 6.2 Merc Horixons
1.5:1 Velvet Drives
Make sure the nuts are in the proper order.
I intend to use several smooth jaw pipewrenches, does anyone happen to know what size the nuts really are? I am 6 hours from my boat trying to make a plan. I do know the nuts seem to be on incorrectly according to the link posted here. The large one is up against the prop. I did not do this, however I am not sure the other side that is holding just fine will get changed. Thanks again for the replies.
The nuts take a 2 1/4" wrench I discovered. I did everything just like suggested and put approx 60 miles on the boat and the nuts are back against the cotter pin again… I am going to use red loc tite and an impact next time I go to the boat. We had 350 ft lbs and the jam nut was tightened against the small nut with two 36" pipe wrenches… I can't believe it loosened again!!!!
The strap wrench worked to hold shaft to tighten the first nut but it is not ideal…...
The strap wrench worked to hold shaft to tighten the first nut but it is not ideal…...
