Prop tuning and grease.

Never have put grease on shafts and props but heard of people doing it to supposedly keep marine growth off of them. Never use anti seize on my props although I guess you could. Its all personal preference.

I wouldn't. They are not splined like an outboard propellor, so they're just relying on the mating surface between the hub and the shaft to keep them from turning (as well as the keyway). What I would do, is remove the keyway, put the prop on the shaft with valve grinding compound inside the hub, and put a nut up there hand tight (so you can spin them without the shaft moving) but tight enough there's a little friction, spin them around a few dozen times, drop props, clean valve grinding compound from both surfaces, insert keyway, install prop and propnuts, cotter pin.

What a complete and utterly back assward way to lap a propeller hub. Where do keep getting these ideas from?

How else do you lap the prop to the propshaft? You put the prop up there without the keyway with valve grinding compound on the shaft/prop hub, and use the nut to keep it from falling off and spin it a bunch of times with some friction from the nut, remove the nut, remove the prop, clean the surfaces, put the keyway back in, put the prop back on, put the small nut and torque it, then the big nut and tighten it against the small nut and put the cotter pin in. You're not going to hold most propellors up there by hand with the shafts in the boat, so you use the nut to hold it up there while you spin it. This is pretty much how every boat yard in South Florida does it from Merritt's to Viking. Perhaps those guys are missing something.

It would be prudent to apply a dye to the taper and slide the prop on and off and identify any and all high and low spots by dye transfer.Without a dye transfer you have no idea what your dealing with fit wise. If it's a classed vessel than you'll be required to have 98% min. mating of surfaces. there's optical machinery available to ensure a perfect mating when the shaft and prop are available in the machine shop at the same time or as a Lloyds surveyor once told me Emory cloth in hand "it's like wiping the dew off of the Rose petals.The prop will be fitted on and off many times and dye will be cleaned and re applied to ensure a complete mate of the surfaces. spinning a prop on a taper by hand certainly has it's size limitations and the number of men needed to do so. Certainly a small boat / prop tech deal but would never " fly" on any substantial wheel. Without a dye process your just guessing at what your starting with and what your finishing with.

In real life I've seen that Prussian blue dye used once. I've also seen numerous yards just simply push reconditioned or new props right up the old shaft and bolt them on without doing anything, many times. At a lot of yards, you're lucky if they get lapped at all. But, of the ones that do lap them, most do it in the method I described above, on the 100's of 100'< yachts I've seen yard workers install props on over the years.

That says more about the standards of the yards you hang around than how it should be done. Bluing is pretty much the industry standard for determining fit, it is how professionals do it.

J,
I'm not talking about Sea Rays or Cabo's here & I'm not talking about ships either, Lets use a 130' Westport for example, if its a commercially registered vessel in the charter trade it will have class surveys at launching and then @ 5 yr intervals or anytime damage occurs to the vessel. Part of the surveys will include the running and steering gear etc. a survey of the propeller fitment to the shaft taper and the fit of mating surfaces will be performed first with a dye to determine the % of mating surfaces & then appropriate action taken that doesn't include hand spinning the wheel on the taper with valve lapping compound. At this time the shaft taper will either be dye tested or magnetic particle tested for cracks and either repaired or replaced depending on tolerance's . Sorry to inform you Capt j but to use your own words "this is the real world" of properly classed vessels.

I understand you're talking about classed vessels. But Hello, this thread is about putting a set of props on a 31' Cabo, not a 130' Westport. The advice I gave the OP is exactly what Cabo Yachts would do and did, because I put dozens of new props on brand new Cabo's for Cabo back in the day and have given solid advice given the OP's boat, a 31' Cabo. All Cabo's shipped without the props installed, as all of them were trucked from the factory and it was up to the dealers to install everything. We used to outfit the Cabo's for most all of the international dealers, there were 3 of us and we'd install the flybridge, all the electrical,steering, shifter connections, props, anchor, etc. in 3-4 days, do the engine startups/seatrials with the various manufacturers, then pipewelders/high seas/ P+R (sometimes Bosch) depending on who the dealer wanted to install that stuff would do their thing, then we'd load them on a freighter.

Why do you guys enter a thread that someone posts about a smaller boat, such as this 31' Cabo, and then insert megayacht or classed advice that is totally irrelevant to what the OP is asking???? I'm surprised you guys didn't tell him he should drop the shafts and take them and have the shafts magnufluxed or x-rayed to make sure there aren't any hairline cracks by the keyway before putting his 22" or 24" diameter props on because that's what classed 130' Westports do.

I've also seen a dozen classed vessels put on props over the years that have never been lapped or anything, because they had a diver install them underwater after they hit bottom in the Bahamas over the years and mangled the old ones.

I've been in and out of all of the big yards in Fort Lauderdale (as well as other places) more times than I can remember. Yes putting dye on the wheels, fitting them, and then seeing the mating surfaces and the high/low spots where they're not making contact is a good thing to do. Then using valve grinding compound and spinning them on the shaft, then doing the dye again once your done lapping them to confirm that the prop has been properly lapped to the shaft to confirm it is a good thing to do. On a yacht under 100' it is rarely done. And on a yacht this size is it really necessary, I'd say 99.8% of the time no. I've seen very very very few propshaft keyway failures over all of the years and thousands and thousands of boats over the years, less than a handful, and most of those were from impact.

Marmot, about the only 2 yards that I'm not in and out of on a regular basis are Bradford and Rybovich. Like I've said, of all the others ones in South Florida, I've never seen them use dye. I've also seen lots of "reputable" yards put props on without even lapping them. Yards are only as good as their lowest paid employees.

The vast majority of vessels owned by people on this site are not classed. The vessel that this thread was regarding is not classed. So, there are many real worlds. There is the world of classed vessels and there is the world of Cabo, Carver, Post, Sea Ray, Bertram, OA, Cheoy Lee, Riva, Sunseeker, Princess and all the other hundreds of boats under 100' and used just for pleasure. You say we're not talking Sea Rays and Cabos, but a Cabo is exactly what we're talking about.

Now, just as some here forget there are multiple worlds, there's a third world that consists of far more boats than these two worlds. That's the world of 30' and under that fills our lakes. That isn't a world for this site. However, both the classed world and the under 100' not classed world are for this forum. That's not even to mention the commercial boats that are operated by members of this site.

As we've not had shaft or prop work done on out boats yet, I can't tell you what procedure our yard uses. However, I know they'll use the procedures you outline at 5 years on the classed vessels. I doubt seriously they'd use it for a routine prop change or tune on our 44' Riva unless there was a problem they needed to address. While we use a yard that deals largely with classed vessels, most yards in South Florida do very little if any work on classed vessels.

OB,
Getting off topic here but just have to say that the vast majority of Rybovich's ( your favorite yard) work load is "classed vessels" Derecktor's also, and I would say they're the two big majority players for yacht yards in So. Fl. until you get to BAE in Jacksonville and you'll find the same there. You misquote me as I said that "I'm not talking about Sea Rays or Cabo's but rather commercially registered charter yachts which if you look at the flag state registries the majority or 86 percent of Cayman and 98 percent of Marshall Isl. registered vessels are commercially registered so then we can have another thread on what takes place for Flag state surveys.

"Yacht Forums" We Know Big Boats!" Don't know if Sea Ray fits the header...

Never heard of "Prussian Blue" so I Googled it and the top four responses came back for Lapping propellers. Funny thing that is...

Yes, I would absolutely advise a vessel owner of any size to have his main shafts or tail shafts MPI'd or dye tested for cracks on the taper every few years as it's cheap insurance over having a failure and the consequences that follow. Just had it done to a 2004 65' Viking convertible @ Stuart Propeller last April at which time they properly mated a new set of Veem Interceptors to the tapers and it didn't have a darn thing to do with fairy dust and hand spinning them.

So how does one expect to know if the mating surfaces are actually mating if no check is ever performed?

Because of advice such as that quoted above of course.

If you don't know how well the mating surfaces fit at the beginning of the process then how do you know if they even need lapping and how would anyone ever know when the surfaces were lapped adequately or are just grinding away and removing metal unnecessarily?

If these other boats don't fit here, then this will become a very quiet forum. And we use Rybovich so fully aware of their yard. But outside the two you mentioned, very little work on classed vessels. Didn't intend to misquote or get off the topic, but we just do need to remind ourselves that in spite of the slogan of this forum, there is a huge population here of smaller boat owners, managers, captains, mechanics, etc. Post gets more conversation than Westport. Cabo gets more than Feadship.

And the proper technique for mating propellers to shafts applies to every one of them. Just winging it by smearing on a blob of valve grinding compound then hoping for the best is not what any owner should accept.

Yet it seems to work perfectly fine on the millions of small boats out there, and none of them seem to be having the props falling off or split shafts from the keyway. Sure is putting dye on shafts the absolute best way to lap a propellor, yes. Is it practical and seen in the real world at 99% of the yards that work on boats under 100', NO. Half of the yards don't even lap propellors on small boats period. I've picked up 2 boats from 2 different dealers yards that put the props on backwards, over the years, to give you an idea of what really goes on in the real world. And, I'm talking about manufacturers, their dealers, yards, etc. Do you have any idea how many owner Captained boats have the props pulled and replaced by a diver. You can actually see how well the mating surfaces are mating by feel and by looking at the valve grinding material on the shaft and hub and the score marks made by it. As you spin the propellor, you'll feel less resistance, so you tighten the prop nut a little more, continue, a little more and then you won't see anymore gains in reduction of friction and you call it good.

Needless to say, I have NEVER, and I mean ever, seen a megayacht engineer changing or lapping their own props themselves. Half of the time they aren't even watching when the props are even being re-installed. If an engineer from a mega yacht is asking how to lap propellors, they're in serious trouble. If the props were being re-installed on the LLoydship I Captain, manage, and maintain, then I'd want dye used, on a 31' Cabo no.

Most of these threads asking for help are from small boat owners, which we'll classify as under 100'. Very few of the posts, especially in the technical discussion are from mega yachts. Prussian blue dye has been the dye that has been used for lapping props for decades now, as well as checking shafts for cracks, etc. glad you finally know the proper name of it. How many small yachts do you guys deal with on a regular basis? What is perfect in theory is not necessarily real life.

Could it be you had the shafts checked because the old set of propellors was ground into fairy dust and couldn't be repaired and that's why you had the shafts checked for cracks and they put a $60,000 new set of props on a $750,000 boat?