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jfdubu

New Stuffing box

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So, I'm committed to replacing my Lasdrop shaft seal with a traditional packing gland. Before anyone asks why, just because but that's not the problem.

My problem is space The Buck Algonquin seal assembly is about 1.5" longer than the old assembly and it doesn't fit. In order to make this work I think I have to move the engine forward about an inch. Other than the normal clearance issues I need to check am I missing any other surprises when I start this? I know I'll be doing a major shaft alignment.

Anything else?

thanks, John

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Yeah - rethink the whole thing.

Move & remount an engine to change to a more primitive seal - Just Because?

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44 minutes ago, SloopJonB said:

Yeah - rethink the whole thing.

Move & remount an engine to change to a more primitive seal - Just Because?

+1

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Can the 'glass tube that transitions thru the hull be shortened?

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The lasdrop assembly has leaked a lot when ever the shaft spins like on the order of 1 gallon/hour. tried 1 rebuild and precise shaft alignment, no change. Last season I had a catastrophic failure and almost sunk the boat, the coupling hose came off the shaft log. Yes this was just the clamps and the wrong hose.A packing gland my be more primitive but I will sleep better.

The glass tube, shaft log is as short as it can be. This length issue may be a factor in why the las drop leaks so much.

I'm also replacing the motor mounts. The only "hard" connection between the boat and motor is the exhaust hose.

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I did this on my Santana 35 I actually got better clearances.  Moving engine forward is ok as long as your shaft / prop has clearance to cutlass bearing. Make sure your new mounts are better or equally screwed in. I added glass to engine stringers to stiffen them

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Strongly suggest you look at the Manecraft dripless solution. It's only 131mm (5 1/16") total overall length, including the overlap on the stern tube. It's a much better design than the PSS product, too.

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Good point, memory tells me I have about 2 " between the prop and the cutlass but that's easy to check. My engine sits on a preformed box, pretty stiff but if I can make it stronger I will. I have an Express 35, yanmar, 3gm30

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34 minutes ago, Moonduster said:

Strongly suggest you look at the Manecraft dripless solution. It's only 131mm (5 1/16") total overall length, including the overlap on the stern tube. It's a much better design than the PSS product, too.

As much as this looks interesting very limited distribution in US and I still see a catastrophic failure potential. Plus I already bought the BA kit and had the flax from my old boat.

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I'm quite confident that far more boats have sunk due to the failure of conventional packing glands than have sunk due to a dripless seal and believe that moving your engine in order to accommodate a conventional gland is an expensive and time consuming downgrade that doesn't materially affect risk.

That said, do not pack with flax; the 20th century has been over for nearly 20 years.

Instead, find teflon packing at a local chandlery or buy from a distributor by doing a google search for PTFE Gland Packing.

 

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Flax is a generic term. I have PTFE packing material. If more boats have sunk with packings than dripless it's more likely because of the 100year head start in use and still a 10x number in use.  Yes, my failure and fear was due to the hose between the shaftlog and seal and wouldn't be a function of the actual seal, dripless or packing, and for the that I've upgraded to the BA hose not the exhaust hose that was on there (don't do that). But dripless assemblies can fail in the worst way and my experience with the dripless was not good. Run engine, pump bilge don't run engine no leaks. I had a packing gland on my old boat (2GM20) and barely a drip with the nut just over hand tight, locked of course.

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If there isn't much space there now, how do you go about re-packing the nut in the future? I've had good luck with the PYI shaft seal: https://www.shaftseal.com/pss-type-a-seal.html and at an uncompressed length of around 7" I don't see how this wouldn't fit considering 1" or more is over the glass tube. 

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3 hours ago, jfdubu said:

Good point, memory tells me I have about 2 " between the prop and the cutlass but that's easy to check. My engine sits on a preformed box, pretty stiff but if I can make it stronger I will. I have an Express 35, yanmar, 3gm30

What is an Express 35?  I have a 37 and know about the 34.

I use a PSS on my Express 37.  I wouldn't want a stuffing box here, the space is pretty constrained and changing the packing would be super annoying.  The PSS was annoying enough to replace with the constrained room.  It's the only part of the boat that I've found so far where access is less than an average boat, most access is much better than an average boat.

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The Express 35 is a Steve Killing design built by Goman Yachts in Canada...

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Yes, that's it.  I really like the boat and how it sails. Little things like this are a PITA but I do have plenty of room to do this. I actually contacted Steve and he send me polars and some  rig tuning info

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23 hours ago, Moonduster said:

That said, do not pack with flax; the 20th century has been over for nearly 20 years.

Instead, find teflon packing at a local chandlery or buy from a distributor by doing a google search for PTFE Gland Packing.

 

While ultimately I agree with you re: flax packing being antiquated..... at the yard I still use flax for most engine shafts- unless the customer specifically requests teflon or the like... simply because I don't trust that they won't over tighten them, causing damage to the shaft. I use teflon/PTFE to re-pack rudder boxes simply because the heat is never an issue there, but, IMHO, the teflon/PTFE requires a modicum more attention than SOME customers/owners are prepared to give... seems not to be the case here, but there are plenty of people out there that would destroy a shaft in a season if left to their own devices...

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15 minutes ago, suider said:

While ultimately I agree with you re: flax packing being antiquated..... at the yard I still use flax for most engine shafts- unless the customer specifically requests teflon or the like... simply because I don't trust that they won't over tighten them, causing damage to the shaft. I use teflon/PTFE to re-pack rudder boxes simply because the heat is never an issue there, but, IMHO, the teflon/PTFE requires a modicum more attention than SOME customers/owners are prepared to give... seems not to be the case here, but there are plenty of people out there that would destroy a shaft in a season if left to their own devices...

Can you elaborate on that difference? I've never heard about the PTFE packing being more sensitive to overtightening.

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1 hour ago, SloopJonB said:

Can you elaborate on that difference? I've never heard about the PTFE packing being more sensitive to overtightening.

While everyone seems to agree that the synthetics WILL last longer and are inherently more slippery, over tightening them can cause so little water to get by that the box can overheat and score/wear the shaft- Passagemaker and ProBoat (at least) have both written about it in the past. Again, if the customer is the type to actually check/adjust their stuffing box AND they request it, I'll certainly install it for them. The customer that blindly checks 'repack stuffing box' every third year on their spring commission sheet- I'll usually just use the flax instead.

My general feeling is (note! this is purely anecdotal- someone can certainly correct me if this isn't the case) that the same thing can happen with conventional flax as well- it's just that the conventional flax will 'fail' sooner, at least partially- allowing some water by, whereas the synthetics just have such a high wear resistance that they don't ever distort enough to let any water past. I've seen plenty of prematurely worn shafts from flax boxes- but (again, anecdotally in my PERSONAL experience) I've seen them happen more often when synthetics were used.

 

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Whatever system is used, I'm in the habit of clipping some big cable-ties loosely over the tube so that, in the event of catastrophic failure, plastic bags can be shoved around the tube and shaft and cable-tied in place, without the drama of trying to fit cable-ties around the shaft with water lapping at your nose.

Cheers

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My own experience is that flax is far more difficult to tension correctly, the difference between a red hot stuffing box and a steady stream of water can be just a few degrees of rotation.

PTFE, by comparison, has a wider range and requires no dripping water to prevent overheating.

 

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I also would not recommend a packing that has both PTFE and graphite has the graphite can cause problems when all the lubricity of the Teflon wears out. You're left with a conductive, abrasive residue. That can cause major shaft problems.

Based on my initial premise I've got some good feedback. If/when I move the engine make sure I check shaft clearance at the cutlass. Hadn't considered that.

Clearance for repacking with the shaft in would be nice but I will to do this every three years or so during winter projects. After I have some measurements to make the verify engine room clearance. Other than that there's no good reason not to procced with my plan. Considering some of the other projects I've done this should be a walk in the park.....famous last words.

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11 hours ago, Moonduster said:

My own experience is that flax is far more difficult to tension correctly, the difference between a red hot stuffing box and a steady stream of water can be just a few degrees of rotation.

PTFE, by comparison, has a wider range and requires no dripping water to prevent overheating.

 

That's interesting... maybe I'll look around and start to rethink the blanket 'rule'... 

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Have you looked at the Volvo unit? Very short.

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Well, I'm not looking at alternatives, No room to move the engine. A detailed inspection of my lasdrop indicates it is just worn out. So It will either be replaced or I'll build my own seal assembly.

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