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Old 07-14-2020, 10:36 PM   #1
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Grand Banks 36 Prop Shaft Packing Gland

Traditional packing gland procedure calls for no leak when stationary..1 or 2 drops per minute and a temp of about 30 degrees F above outside water temp when rotating.

Since the GB has the extra coolant flow from exhaust cooling water, I assume that the GB gland can be a little tighter with no leaks while rotating as long as temp is less than 30 deg F higher than outside water????????

Oxford Yacht claims to be expert on GB and they speak to having drips when rotating.

Before I bought my boat the previous owner replaced packing gland when cutlass bearing was replaced. Ran for a while with no drips ever, then the lock nuts backed off from vibration and it began leaking.
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Old 07-14-2020, 11:05 PM   #2
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Quote:
Originally Posted by stroutmail View Post
Traditional packing gland procedure calls for no leak when stationary..1 or 2 drops per minute and a temp of about 30 degrees F above outside water temp when rotating.

Since the GB has the extra coolant flow from exhaust cooling water, I assume that the GB gland can be a little tighter with no leaks while rotating as long as temp is less than 30 deg F higher than outside water????????

Oxford Yacht claims to be expert on GB and they speak to having drips when rotating.

Before I bought my boat the previous owner replaced packing gland when cutlass bearing was replaced. Ran for a while with no drips ever, then the lock nuts backed off from vibration and it began leaking.
Not sure what you mean by..."the GB has the extra coolant flow from exhaust cooling water"...as for mine, unless you have an actual water cooled bearing, as many of the newer, so-called dripless seals have so dripless can be achieved, you are always going to need at least a very slow drip from the gland to ensure adequate lubrication of the shaft. However, I didn't own a GB, so maybe they are different..? But I find it hard to envisage just how the engine/exhaust coolant could be being diverted through your gland seal.
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Old 07-14-2020, 11:29 PM   #3
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https://oya.com/maintenance-reduction/shafting-issues/

The above link will take you to article with drawing of the GB stuffing box...it has a water cooling hose that provides cooling water flow to the packing...essentially the cooling flow is to cool the stuffing box metal housing.
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Old 07-14-2020, 11:32 PM   #4
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The GB boats "stuffing box" are all water cooled from the exhaust riser water.
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Old 07-15-2020, 12:24 AM   #5
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I use Duramax stuffing and mine does not leak, at least they didnít until I repacked one. Duramax says run it 5 to 10 hours before tightening it up. I am about there now with the hours. They never leaked a drop at all. I have traditional stuffing box with water injected at the rear of the box. My shaft looked perfect when I rebuilt it. I replaced the hose and clamps also over the winter when I had the port engine out, much easier access.
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Old 07-15-2020, 04:40 AM   #6
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If you decide to repack use the Duramax as stated as above. Great stuff, won’t drip, and probably out last you and me. DO NOT OVER TIGHTEN WHEN INSTALLING THE DURAMAX. Run it in Loose for hours. It will leak while it is running in. Then just gradually tighten.

You can tighten the existing packing a little to try and stop leak. Drips won’t hurt anything. Heat will. Tighten gradually and watch for heat while running. Should be max roughly 100 degrees or so. IE able to hold with your hand.
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Old 07-15-2020, 07:09 AM   #7
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https://www.duramaxmarine.com/shaft-ultrax.htm

Duramax sure seems like a good solution.
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Old 07-15-2020, 12:09 PM   #8
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I use Duramax stuffing and mine does not leak, at least they didnít until I repacked one. Duramax says run it 5 to 10 hours before tightening it up. I am about there now with the hours. They never leaked a drop at all. I have traditional stuffing box with water injected at the rear of the box. My shaft looked perfect when I rebuilt it. I replaced the hose and clamps also over the winter when I had the port engine out, much easier access.
The GB36 setup is similar to your pic but has the water injected closer to the packing---in fact just behind it.
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Old 07-15-2020, 12:13 PM   #9
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https://www.duramaxmarine.com/shaft-ultrax.htm

Duramax sure seems like a good solution.
Hard to tell for sure what packing material in my stuffing box, as previous owner tells me that it is more than 10 years old. I think Duramax is the only material that could last that long.

Most likley my problem with a leak stemmed from a repair facility replacing rhe rear motor mounts--probably loosened packing gland to move shaft and then failed to tighten the double nuts sufficiently.

So in essence, I will just monitor the housing temp and adjust to no stationary shaft leaks and housing temps less than 30 F above the outside water temp.
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Old 07-15-2020, 01:34 PM   #10
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Depending on use, almost any packing can last 10 years.

I will bet both my last boats had 10 year old packing in them. I dont think most sweat it till there is a serious issue.

Not many people use Duramax in my experience.
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Old 07-15-2020, 07:32 PM   #11
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Traditional packing on that setup should last 3 years (depends on use). Tighten a few turns in between. Literally takes about 10 min to pull out the existing packing and replace it. Cut the new packing the same length as the old, place 4 new rings in, staggering the opening. Do it once and you may actually look forward to it the next time. Make sure you get the right size of packing. Water will enter the boat, but itís easily manageable for your bilge pump (test before).
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Old 07-18-2020, 02:39 PM   #12
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Just finished running and measured 80 F water, and packing gland housing 110-115 F after running at 1800 rpm for 30 minutes..no drips running or stationary..I think it is good.
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