Lifting the aft end out of the water in the slip - SailNet Community
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post #1 of 27 Old 01-07-2012 Thread Starter
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Lifting the aft end out of the water in the slip

This might be a stupid question but I'm a noob so here goes.

Due to an improper repair by a past owner and subsequent near catastrophic failure of the stuffing box tube (see earlier posts), I have decided to replace the assembly with a PSS dripless system. That's not the stupid part (although there are some here who might disagree).

The only way for our local marina to get the boat out of the water is to hook up their gooseneck triple axle trailer and haul the whole boat onto the yard. This takes three people, with at least one of them getting wet to adjust the supports prior to the final drive out. I don't mind paying for it, but the marina owner is not enthused about doing it. This seems like a lot of effort for a half-day's job.

Here is the potentially stupid question. Since I really only need to raise the aft of the boat enough for the stern tube to clear the water and not sink my boat while I am doing the repair, is the haul out really necessary? Could we not rig an A-frame or something on the dock with straps that will be capable of lifting the boat safely and far enough to clear the waterline? The boat displacement is 6000 lbs, but if only the aft end were lifted a foot or so, the weight on the dock and contraption would be a fraction of that, correct? It's been awhile since college physics, but if the weight were lifted on the aft, wouldn't some of the weight be distributed forward to the water supporting the bow? The base of the keel would probably still be in the water or just above it.

Has anyone tried something like this?
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post #2 of 27 Old 01-07-2012
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I have actually installed a knotmeter transducer by supporting the bow of the boat with a crane and slings and letting the tide drop away until I could get under with a dinghy.. it was ultimately successful but in hindsight it was probably not a very clever thing to do... one slip or failure in the support structure would have been catastrophic. The things we can get away with at times.... I sure wouldn't try it again - btw this was on a similar displacement boat.

The problem with such a plan - or even planning to do such a job on a tidal grid is that there's no room for error and any delays or glitches you may run into are difficult to accommodate.

What you're contemplating is a complex job.. the shaft coupling needs to come off, the shaft retracted (but not dropped to the bottom) - is there clearance for that between the prop and the rudder (or the strut and zincs??)

Too many variables... never mind the safety aspects....

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
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post #3 of 27 Old 01-07-2012
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Faster is right. I am in the middle of this repair myself. I would find a place where you could haul it out of the water. There are too many variables that could affect how long you will be involved in this repair.

In theory, from the outside (in the water) you could also stuff material between the prop shaft and the shaft tube, then let the bilge pump take care of the inevitable water ingress, but I would not recommend anything less than pulling the boat out of the water.

Last edited by jameswilson29; 01-07-2012 at 05:43 PM.
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post #4 of 27 Old 01-07-2012 Thread Starter
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Thanks Faster,
No tides, we are on an inland lake. But any wake could cause the boat to move in relation to the dock, adding stress to the rig.

I am also assuming that everything will go smoothly, which is a huge assumption with a 26 year old coupling. I would also have to get to the shaft and remove the zinc that is directly in front of the prop strut.

Sometimes you have to write a thing out to see the error of it.

So, if I am hauling out is there a list somewhere of things I should check so I don't have to do it again soon?
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post #5 of 27 Old 01-07-2012 Thread Starter
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Thanks James. Good luck with your repair. Be sure to post some pics so I can see how to do it right.
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post #6 of 27 Old 01-07-2012
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You know, I think you could do it. If the front end could be secured, you could lift the rear a wee bit. She'll want to move forward, but you could restrain her, I guess. It would be unorthodox!
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post #7 of 27 Old 01-07-2012
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What model boat is it/what is the hull shape?

Given that you have an inboard this is unlikely but some boats can actually be winched up a beach on rollers quite easily.

As others have stated, it is always better to be safe than sorry. If you are going to try something, you might want to look to see how your insurance would handle it. I have always used a rule of thumb that if I have to ask others how to do something since I can't figure it out myself, maybe I shouldn't be doing it.

Have you called around and seen whether there are any other local hauling companies? There are many ways to haul a boat depending on the setup including trailer, crane, forklift, marine railway etc.

Good luck.
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post #8 of 27 Old 01-07-2012
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RE: Installing the PSS: If you have not already done so, read the article here: PSS Shaft Seal Installation Photo Gallery by Compass Marine at pbase.com. In particular, I strongly advise you add the clamp collar as described in the article, as in this photo:
.

A few months ago, my PSS rotor slipped slightly, leaving a gap between the rotor and the bellows...as I was leaving the boat, I heard water running...the washdown hose was turned off, so...after a few seconds tearing open every access panel I could, I found this problem. Say ~100 gallons came onboard in ~5 minutes; the flow stopped as soon as I pushed the rotor tight against the bellows again. Fortunately no harm done (except to my nerves), replaced the grub screws and re-adjusted. However, the clamp collar would have prevented this near-disaster.

BTW, the PSS seal works great, and the folks there are very helpful. I am just not convinced about having the safety of my boat dependent on two small grub screws...
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post #9 of 27 Old 01-07-2012
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Bloke down the pub says you can use the wax gasket from a toilet mashed around the shaft to create a decent seal while you work on the stuffing box.
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post #10 of 27 Old 01-08-2012 Thread Starter
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Quote:
Originally Posted by paul323 View Post
I am just not convinced about having the safety of my boat dependent on two small grub screws...
Thanks Paul, your experience will be in my mind while I plan this upgrade. Did your SS ring have just the two set screws? The PSS sold now have a second set of locking screws as well. The insurance of the locking ring seems well worth the money.
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