Shaft Log: questions

[chuckm]

Re: Shaft Log: questions

Yes, over my head and going down for the 3 rd time. Which is why I have'nt done any real bulding or drilling yet, instinctively I believe in " make mistake slowly". But do not be to alarmed: as The Kabota diesel came out of a sunk fiber glass sailboat from one of the hurricaines, paid 150$. The Lansdrop Gen 11 seal I found on ebay for a pitance, The SS shaft I traded extra lead for, and the Hurth tranny also found on Craig list for @ 250$. So far wife is still clueless to above expenses, thats the real danger. I did see two Cutlass bearing on E-bay, Doris or debie, any way 1 1/4 inch for 49$ apiece so all is still in real of mad money. Mad as in crazy being the pretence statement.

[seo]

Re: Shaft Log: questions

Ian,
I was a little surprised just a week ago when talking with the head engine installation guy at Billings Diesel, in Stonington, ME. If you look at their website

http://billingsmarine.com/

I think you'll agree that they do all kinds of work on a remarkable variety of vessels.
Anyway, his preferred shaft installation in a lobsterboat or dragger is a cutless bearing at each end of the shaft tube, hard-mounted stuffing box, hard-mounted engine. I inspect lots of small commercial vessels on the Maine coast, and see that arrangement some. It's certainly how it was done on every single large commercial vessel (research, cargo, towing, tanker) that I've worked on or inspected.
Which doesn't mean that I'd recommend that approach, but if that's what a guy wants, it can be made to work. There isn't a lot of room for error.
Day before yesterday I was talking to Glen Holland at his boat shop:

http://www.maineboats.com/boat-launchings/muskrat

asking him about how he does boat installations. He's a soft mount engine & stuffing box guy.
I've personally had good luck with this approach, particularly in sailboats. All of my professional training was acquired while growing up on a farm in Minnesota, but over the last 30 years I've installed, operated, repaired, owned, and surveyed a lot of machinery installations. So I try to keep it as simple as possible.
As far as the boat under discussion in this thread, I must admit I don't know what a John Gardner "Garvey" looks like, and the one very small picture isn't very informative.

[boattruck]

Re: Shaft Log: questions

Chuck, Have you found the Buck Algonquin website/catalog? They have some tubes, and I'm sure if you speak with them live they can help you navigate the challenges of your build. You really dont want to build some swiss watch system here, one stern bearing, a stuffing box to keep the water on the outside. Align your engine to the face of the shaft coupling, and you are off to the races, soft mounts work just fine, it will outlast us all... Cheers, BT

[seo]

Re: Shaft Log: questions

There are four specifications that the "Debbie," "Dinah," nomenclature covers:
1) Shaft size
2) Outside diameter (inside diameter of any bearing carrier you have)
3) Length
4) Material. The outer tube can be brass or FRP
I don't think $49.00 is a bargain for a cutless bearing...

[Ian McColgin]

Re: Shaft Log: questions

seo, Billings is certainly tops. I'm not a mechanic, just a sailor and aside from tug boating (and not in the engin room), driving launches and a season of charter fishing, I've little power boat time. Perhaps it's that sail boats have such different problems. It would be interesting to see if they treat the relatively light engins and light loading of an auxillary, where the engin might be called on to work at 45 degrees heel, differently.

I'd not thought to ask chuckm what sort of boat - just projected on the basis of my mechanically limited but in the rhelm of auxillary sail to 20 tons pretty extensive experience. Goes to show the limitations of not having a systematic and broad training.

[Roger Long]

Re: Shaft Log: questions

I was talking to Glen Holland at his boat shop... He's a soft mount engine & stuffing box guy. I've personally had good luck with this approach..

So have I. These three boats, starting at 1200 horsepower, all have a single bearing in the strut with the engine waggling around on soft mounts. No flexible couplings, just a standard hard coupling at the transmission and a flexible stuffing box. The first is going on two decades of service and being repowered, last I heard, at Billings. These boats are remarkably smooth. I have a video of one somewhere with a cup of coffee sitting on a quarter bit while running at 20 knots and there aren't even any ripples on the surface of the coffee.







Same set up as most sailboats including my own and hard to beat. Boats like lobsterboats with their engines well forward can't do it because there is a limit to how much shaft you can have between bearings. Once you've put that second bearing in, you have to either hard mount the engine or go to complex flexible couplings and Aquadrive like setups if you want to prevent transmission of any but just the highest frequencies. I've often gone up on shaft diameter just to be able to retain this simple shaftline arrangement. A larger shaft is way cheaper than all the other stuff involved in a two bearing set up. However, with a forward engine location, the shaft gets too large.

[wizbang 13]

Re: Shaft Log: questions

Seo, How does it work with a cutlass bearing forward of the SB? It would be dry!

[boattruck]

Re: Shaft Log: questions

Wiz, If a boat has a long section of unsupported shaft, think fishboat, down in the shaft alley, etc it can have intermediate bearings, sometimes called pillow bearings, the ones I've seen and worked on are iron or steel housings that is shimmed and bolted to floors, with greased roller bearing insert. The whole thing obviosly needs to be aligned well. I have seen one or two water cooled bearings at the forward end of shaft tubes, and they have been trouble in those few instances, not enough water flow in this area in my estimation... Certainly not needed in a boat with a 4' shaft length... Cheers, BT

[seo]

Re: Shaft Log: questions

Boattruck has it right. They're often called carrier, or intermediate, bearings. Babbit pillow blocks were pretty standard, replaced with self-aligning ball bearings. The virtue of the babbit pillow blocks is that they were in two pieces, so could be replaced (or new babbit metal poured in situ), without sliding a new bearing the length of the shaft. Now then have two-piece roller bearings that can have a two piece housing, so easy to replace. Absolutely not needed for a 4' shaft.
Here's a picture of a typical shaft installation in a lobsterboat. Soft mounts, FRP shaft tube. The stuffing box will be a self-aligning box on a rubber hose, not yet installed. B-model Cummins, ZF gear. The open mount hole on the back of the gear is for the power steering pump, I think.
SEO

http://s1191.photobucket.com/albums/z477/se02/boats/?action=view&current=IMG_0100.jpg

[seo]

Re: Shaft Log: questions

Nice looking boats, Roger. Are those alu hulls?
Mainly I'm fooling around with pasting pictures right now, but here's a kind of interesting picture.

http://s1191.photobucket.com/albums/z477/se02/boats/?action=view&current=IMG_0062.jpg

I'm not having much luck with this attaching pictures business. In the post above it linked all right, but didn't display the picture, even though I selected WYSIWYG. This is even worse, but if you past the url above into a new window it ought to display.

This is a picture of the stern bearing and prop of a sistership of the Holland 32 pictured in post #24 above. You'll notice that there isn't a stern bearing housing bolted to the back of the keel (sternpost, whatever you'd like to call it...) Instead, Holland simply takes the FRP stern tube, and glasses the stern bearing to the back of it, then installs the tube and bearing into the hole bored through into the hull, and builds up a strong FRP laminate around the bearing. There are a couple of set screws threaded into the FRP, and nosing into the bearing liner. The drill for replacing the bearing is to pull the shaft, put some dry ice into the bearing, and warm the outside. That gets it out. To install the new bearing, put it in the freezer overnight, warm the housing with hot water, and slide it in.
This is a pretty aggressive approach to reducing the turbulence around the prop. The rather elaborate 5-blade prop in the picture is turned by a 425 hp Cat 3126, and will go over 30 kt.

[Roger Long]

Re: Shaft Log: questions

I'm not having much luck with this attaching pictures business.

It's dead simple. Just type "[img]" in front of the link and "[/img]" directly after it. You have it right in your post but typed "url" where you should have typed "img". Either that or you clicked the link button instead of the image button. Easier just to type directly.



Yes, those are aluminum boats, part of my 80-90% market share in additions to the coastal research vessel fleet over the last two decades. They also have 5 blade props and single struts. I'm with Glen on clean flow to the props. These two boats that you've probably seen have their skegs offset outboard of the props with single struts so you won't have all that structure slowing down the water to the wheel. The smaller one went a knot faster than predicted. It also makes them more likely to shed pot warps.





Note in the second picture that can be clicked to at your photobucket site that the coupling is a plain steel coupling. No flex coupling or even a Drivesaver. That's the way you do it folks.

[seo]

Re: Shaft Log: questions

Thanks for the link tips, Roger. Still practicing. Here's another photo of the Holland boat:

[img="http://s1191.photobucket.com/albums/z477/se02/?action=view&current=IMG_0107.jpg/img]

Some other good things about this installation are:
1) Use of a split shaft flange. Also sometimes called a "Kahlenburg" coupling, because that was the company that made them. In this design, the shaft is clamped into the coupling by the pair of heavy bolts that run perpendicular to the shaft. By loosening the clamp bolts the flange can be taken off without needing a three-jaw gear puller, which can be very hard to use in the space often found around the back of a marine reverse gear.
2) The use of welded aluminum angle brackets that are bolted to the inside of the engine beds, instead of just fitting the mounts to the top of the beds. This has several good results:
a) The brackets can be easily adjusted up and down by drilling new holes, which can be very useful when repowering a boat.
b) The beds can be deeper, which adds longitudinal rigidity to the hull right where it's needed, under the heaviest item in thos (engine).
c) The beds are set wider, which makes access better. When the beds are set in right under the engine mount brackets they impinge on the starter, and often on various pumps and coolers that are often mounted down low on the engine.

OK, now we'll see if the link works...
SEO

[seo]

Re: Shaft Log: questions

Try that again...
[IMG][/IMG]

[seo]

Re: Shaft Log: questions

EUREKA!!
High fives! Pats on the back!! Senility postponed!!

[seo]

Re: Shaft Log: questions

"Kahlenburg" couplings are an extra cost option, but unless you have really good access to the back of the engine they're worth the price.