Laptop 3 blade classic lapping hub/shaft while in water

[fstbttms]

Originally Posted by phorvati

I'd rather not bite into the hub or shaft with the pipe wrench.

Not only am I a PYI-recommended installer but I have installed many dozens of Max Props underwater using this method with a 100% success record. You need to completely immobilize the hub while torqueing the nut. I suspect a strap wrench will not do the trick. But it's your dime.

[mlydon]

Btw - around here in NY, you can get a short haul for about $12/ft - where they block your boat, and you’re on the hard for a week or whatever. A short stay in the slings for an hour while you lap and install the rebuilt prop will only cost you a hundred bucks or so - dead cheap compared to if you drop something while installing in the water.....

Matt

[phorvati]

Originally Posted by fstbttms

Not only am I a PYI-recommended installer but I have installed many dozens of Max Props underwater using this method with a 100% success record. You need to completely immobilize the hub while torqueing the nut. I suspect a strap wrench will not do the trick. But it's your dime.

I will watch your video diligently, it is very helpful, thank you for that. I will make a note exactly where you use the pipe wrench. I am just very paranoid to make sure I don't cause damage.

[AndyEss]

Instead of a pipe wrench, you might buy chaingrip pliers to hold the shaft to keep it from turning.
Chaingrips look like a visegrip but instead of jaws, the gripping action is provided by a chain similar to bicycle chain, but with protruding pins:
https://www.dakotariggers.com/assets/images/20R.jpg
I used chain grips extensively in my business because they do not marr machined surfaces anywhere near the amount a pipe wrench can.

[fstbttms]

Originally Posted by AndyEss

I used chain grips extensively in my business because they do not marr machined surfaces anywhere near the amount a pipe wrench can.

There is an unfinished, non-bearing surface on the Max Prop hub that is perfect for use with a pipe wrench. Slight marring caused by the judicious use of a wrench on this surface will have no affect on the operation of the prop.

[AndyEss]

Originally Posted by fstbttms

There is an unfinished, non-bearing surface on the Max Prop hub that is perfect for use with a pipe wrench. Slight marring caused by the judicious use of a wrench on this surface will have no affect on the operation of the prop.

Thank you Fstbttms for providing the photo of the exact location where a pipewrench can be applied to hold the Maxprop hub. Since my boat also is propped with a Maxprop, this is very useful information. It looks like a pipewrench is the proper tool for this job.

Chaingrips are a $25 tool and they are extremely useful in unusual situations for gripping and holding. I’ve never liked strap wrenches because they have such poor holding power. My toolboxes and home tool kits (I’m retired, but chaingrips were an essential tool in my business tool kits) always include a chaingrip, even if I only use it once a year. But for that one use, they pay for themselves many times over.

[longjonsilver]

Originally Posted by fstbttms

There is an unfinished, non-bearing surface on the Max Prop hub that is perfect for use with a pipe wrench.

i notice on some of your vids that it appears that you are using a hooka. True? or an optical delusion?

jon

[fstbttms]

Originally Posted by longjonsilver

i notice on some of your vids that it appears that you are using a hooka. True? or an optical delusion?

True.

[phorvati]

On a side note, its going to cost 2700 to rebuild the prop. Need new blades as gears on my old ones are so worn, it is beyond repair. I knew it was loose, but being my one and only time of owning a maxprop, I didn't know what and how loose my gears were. Apparently it was bad and this explains vibrations.
He also said hub is good and that the fact my hub came off without a puller, meaning it was loose, it doesn't look like keyway was damaged at all.

[phorvati]

So i got the prop in. Damn river here in Warren RI has a curve ball in flood/ebb predictions. Ebb came much faster than i anticipated and I had to rush.

At slack I torqued the nut as you said, thank you so much, fstbttms for the videos and advice. With a large breaker bar and 1/2" drive socket I was able to put good torque on it. I actually used pipe wrench on the hub's outside/forward surface. Its the moving part of the hub just ahead of the two spinner halfs. I was worried about slipping on the stopper with a pipe wrench.

But by the time I got the x-mark/cone gear in and assembled the spinner halfs, ebb/river current started and i never realized how fast it accelerates. So I lined up the Y mark on the spinner halfs and also the dimples between the spinners and hub, went back up to the dock to prepare the 3 blades and cap in feathered position. This is an 83mm hub with 21" blades, so yes heavy for one hand never mind the river. I though about it as at that point it was all out river ebb. And as i placed the feathered blades and cap into it i thought I still had the Y mark but as i learned later it rotated about 1/2" without me realizing. Needless to say, I test drove yesterday and I was way over propped. I got black smoke at anything more than 1000 RPMs, and i could not go more than 1200RPMs. unless i was motorsailing.

I was convinced I did it right as this was the 4th time of assembling the prop. however the first one underwater and especially with the fn river.

And then this morning at nice calm slack i went back down to see the Y mark off by about 1/2". PYI Video said i can just pull back the cap and blades about 1/2" and line the Y mark without taking them off. that is exactly what i did and now my feathered position is also lined up with dimples between the spinner half's and hub. I did not go for a test drive yet. I think he river must have rotated the spinner halfs by the time i went back with blades in my hand. And then i was trying to hold for dear life while putting the screws back in

But my question is 1/2" (radially) offset in Y mark on an 83mm hub, how many gears of pitch is that? Or its not relevant because my X mark (conegear) was already set at X=N, 18deg, (for a 21" diameter LHR prop), and Y is supposed to be B but it ended up being soemthing else.

My typical cruising PRM is 2100. the fact that i was only able to make 1200(with black smoke) tells me I must have been way over propped.

[fstbttms]

Did you mark the hub end/spinner halve with the blades feathered fore and aft before the blades were inadvertently moved?

[phorvati]

Originally Posted by fstbttms

Did you mark the hub end/spinner halve with the blades feathered fore and aft before the blades were inadvertently moved?

I did not need to add additional marks. The marks have been there since before my ownership (2016). They were stamped in bronze on spinner halfs and hub. And respond to Y=B. And that is the feathered position.

[fstbttms]

Originally Posted by phorvati

I did not need to add additional marks. The marks have been there since before my ownership (2016). They were stamped in bronze on spinner halfs and hub.

Then it should be easy to reset the pitch to the original Y coordinate:

1.- Align the marks on the hub and spinner halve

2.- Loosen the six end cap screws (but do not back them out all the way) and pull the end cap far enough off the spinner halves so the blades can rotate independently

3. Rotate each blade to the feathered position, making sure the hub/spinner halve marks are still perfectly aligned

4.- Push the end cap back down onto the spinner halves and tighten the six screws

[phorvati]

Originally Posted by fstbttms

Then it should be easy to reset the pitch to the original Y coordinate:

1.- Align the marks on the hub and spinner halve

2.- Loosen the six end cap screws (but do not back them out all the way) and pull the end cap far enough off the spinner halves so the blades can rotate independently

3. Rotate each blade to the feathered position, making sure the hub/spinner halve marks are still perfectly aligned

4.- Push the end cap back down onto the spinner halves and tighten the six screws

That is what I did. I am going to go for a test drive to find out if that fixes my problem.

Is it reasonable to assume that being off that Y mark by about 1/2" can lead to that much of a difference in being over-propped. I could only go to about 1000RPM and if i pushed it, I would get black smoke and not go beyond 1200RPM. My typical cruising is 2100 RPM.

[fstbttms]

Yes. In fact it is reasonable to assume the blades each moved into different settings. No reason why they wouldn’t. You may not have had any coherent pitch at all.