Prop shaft seal options for super tight space?

[Alex]

Hi.

I’m still battling with “what should I do about the dripless?”

My gears are so close to the shaft log that only about 2 inches or less on Stb of shaft are showing between the Tides Marine seal flange and the shaft coupler (solid).

Which means that the only way to change the seals is to lift the rear of the engine/gear about 8 inches and work under that load to remove the shaft coupling with a puller etc, impossible. Which I have attempted to do and failed twice in the last month with a cross beam and comealong. Another reason why Im pulling the engines.

I’m in the process of removing the engines and gears to:
Do some engine maintenance (crank shaft seals, pumps etc)
Do ZF maintenance (input and output seals, shift lever)
New engine mounts
Paint bilges
Wiring
And deal with the dripless

1. If I stick with the Tides Marine, which is the easier option now, I would simply change the current seals, polish shafts etc and hope they last. Any seal change after that will require engines to be removed again.

2. If I trash this system and go with a traditional packing gland (with teflon impregnated packing or similar) it will be more expensive up front/now but would be easier to change packing in the future.
Adjustments of the gland nut will be super difficult due to space constraints, but eventually doable. Will need to remove Stb Aftercooler and Prt exhaust elbow from turbo to get in there tight.

Please help as Im loosing sleep over this!

Determining factors: How often will I have to change the Tides seals? Pulling the engines again in how many years? (5years is ok, 2 is not!) Can traditional packing be dripless while running and at rest?

Planning of running engines about 16hrs a month, between a fishing days and leisure.

What should I do?????

Luhrs 32 Open, 6BTAs, ZF220A, 1.75″ shafts with solid coupler and what seems to be a nut on the end of the shaft within the coupler. Space currently available = almost 0

Topic

[Alex]

Hi, Im back with more measurements.

These are the ones noted as “Pending” in my previous post.

Rear of silicone hose on stern tube to rear of shaft coupling:
Port 9
Starboard 8

Overall Tides Dripless assembly length: from rear/end of silicone hose at stern tube to front face of seal housing/carrier.
Port and Starboard 6 – 3/4

Seal housing/carrier alone length: based on what I could feel under the silicone hose attached. This is the heart of the Tides seal system/plastic piece.
3 – 1/2

This would basically be the minimum length the seal housing assembly would stick out in front of the stern tube if the housing was butted up against the stern tube.

Minimum clamp surface needed on stern tube (two hose clamps):
1 -1/2

Since the stern tube has some studs and nylocks sticking forward impeding its full length use back to the hull structure, I would leave as much stern tube as possible available. At least 2 to 2-1/4 to slip on the hose and clamp. Right now the stern tubes still have 1 – 1/2 inches exposed between the hull and the silicone hose.

Don’t know if any other system is shorter in length than 6 -3/4″ with the stock bump hose. Or 5″ with the seal housing of 3 – 1/2″ + 2″ of free hose (straight hose) to clamp on stern tube was used, eliminating any stern tube to seal housing gap.

[Alex]

Tony, I have some measurements although I somehow missed measuring the overall length of the Tides assembly currently in place to compare to the overall length of a traditional stuffing box. And I also measured to the shaft coupling flange, not the shaft coupling piece itself as you asked for. My bad, I will return to the boat sometime mid week to get the missing measurements.

All measurements in inches (“).

Rear of silicone hose clamped on stern tube to back face of prop shaft flange (where bolts go in):
Port 12 – 5/8″
Starboard 11 – 5/8

One inch difference back there but when I measure the engines from the front serpentine belt cover to the hull rib/half bulkhead structure just in front of the engines the measurements are: (This rib/bulkhead is only as tall or goes up to the center of the crankshaft, so most of the front of the engines is exposed with about 12” forward of them above the crankshaft.) (6bta)
Port 5 – 1/8
Starboard 5 – 3/4

What is the bare minimum space needed here to remove the steel serpentine belt cover and service the front of the engine?

So the hull is obviously not perfect but no boat is anyways so I guess they had to install them like this to match props/struts at the rear. The boat is in brackish water so there is no way for me to go and measure struts and prop gap etc without hauling out. Still I could pull the starboard motor forward another inch to match the port distance from the “Rear of silicone hose clamped on stern tube to back face of prop shaft flange”.

Stern tube OD:
3-1/2

Stern tube still showing between the hull structure and the silicone hose:
Port 1-1/2
Starboard 1-1/2

Tides Marine seal carrier housing OD:
3

Shafts OD:
1-3/4

Rear of silicone hose on stern tube to rear of shaft coupling:
Pending

Overall Tides Dripless assembly length:
Pending

[Tony Athens]

Dripless seals–My opinion

I mhave deal with two kinds of dripless seals over the past 15 yeras or so… PSS & Tides……………

Tides units seam to have a good following on some local high-annual hour commercial bosts local to me–It was the Customers choice to but & install them. The 3 unit I know of have done theoir customers well and all have good access & rom to deal with what ever need to done.. East Coast hulls that operate in the 12-818K range..

As to PSS— As reluctant as I am about using them, we have installed many and continue to do so today–The customers want “dripless”…Advertising by PSS is doing the job……We do tweak the installation protocol some to make up with what we feel are obvious shortcommings based on dealing with them for many years………….The big ones are we use gease to install to rotating collar ( under the o-rigs & on the shaft) and feed the unit with restricted water flow, plus a couple of other tricks……………….So do they work well– I must say they do but if something does go wrong, you better have a quick in-place back-up plan and be looking for a close haul-out place………….

My own boat–No-way!

My bro’s boat that has loogged over 60,000 hous in the past 23 yrs on the same 2” shafts & props–No f-ing way..

Any serious off-shore boat–NO WAY..

[Alex]

I would have to agree Rob, The tides dripless is a bit more complicated in its nature with the front flange screws, retaining washer, water hoses to and from one seal to the other. If it fails catastrophically while underway and I notice it on time… the only viable option is to gun it to the nearest marina and call for an emergency travellift service hoping the pumps keep up during that run.

[Rob Schepis]

A bonus for going with a traditional stuffing box in your situation Alex is that you will never have a dangerous “total failure” situation. A dripless shaft seal can have a catastrophic failure and in the tight space you have it would be very difficult to triage the situation.

[Alex]

Thank you Tony. Great article on the propeller shaft packings and how you lathe turn the hose barb.

From my pictures it seems I could cut the stern tube back another inch (leaving 2″ for the hose and clamps) and that would give me that extra space I need to then make decisions.

Hopefully I make it to the boat tomorrow Sunday and get the measurements you noted in the photo.

[Tony Athens]

Dealing with a packing gland

Look at the picture. If you drop me a note, I’ll do some measuring when I am back in the shop next week.

The glans we do are 100% leak free at the dock–The key is if can you keep them greased…… close to leak free when running after a few adjustments———10-20 years /10,000 + hrs no issues

Packing a Packing Gland

Packing Glands & Grease a ‘Winning Combo’

Everything you Need to Know about Propeller Shaft Packings

[Alex]

These photos show the current situation with the shafts and general space constraints.

Photos taken with aftercoolers, heat exchangers, turbos and exhausts removed.

This is not the real access I will have once its all back together but shows the area in question.

The current Tides seals are water cooled, the traditional ones are not unless I consider the Buck A models which do have water cooling but are almost 12″ long and will not fit in my space.

So its either the current Tides Marine with water cooling or traditional without water cooling at 2,500-3,000rpm!

Thank you!

[Author]

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