Shaft logs

[Rivertender]

I have been struggling for a long time with "dripless" shaft seals..that drip. Lot of work done by a competent yard, still a problem. I know that a number of owners use the dripless and it works fine, but I havent had that kind of lucik. Aligned the engines, still a problem and I don't want to pull shafts. Yard says traditional shaft logs are way more tolerant of not perfect shafts, props.

Yard recommending converting to teflon traditional shaft seals/logs that are easily adjustable.

Just wanting an opinion on the teflon traditional seal. I hear they are good, but want to hear what you folks have to say. Yard, that handles sizable boats routinely, says about 80% of the boats he works on are traditional shaft logs/20% are dripless.

Thanks for thoughts and opinions.

 

[ttmott]

First the shaft must be centered in the log as the seal assembly mostly centers on the log.
If the assembly is installed not centered, then the shaft will be pressing the seal assembly laterally and eventually wearing out the Delrin bearing then the seal will definitely start to leak.
When we had my boat apart I made a centering tool that aligned the shaft to the center of the log; then the engine was aligned to the shaft with the tool installed. But yes the boat must be hauled for this.
Edit - there is a pic of the tool installed for the bedding of the strut but same tool for engine alignment:

 

[Golfman25]

First, what kind of "dripless" seals do you have? When do they leak? I believe the mechanical face seals (PSS and Lasedrop) are more tolerant of out of alignment conditions than the lip seals (Tides).

If you go with traditional logs, you'll actually need a drip to keep it lubricated. You could try the gore dripless packing. But I found that will leak and need adjustment as well. There are pros and cons to everything.

 

[hottoddie]

I bought a my 37 year old Sea Ray 13 years ago. It had the old style Tides Strong Seals in it when I bought the boat. !3 years later they have yet to leak a drop. I don't understand why people have trouble getting dripless seal to work properly.

 

[ttmott]

First, what kind of "dripless" seals do you have? When do they leak? I believe the mechanical face seals (PSS and Lasedrop) are more tolerant of out of alignment conditions than the lip seals (Tides).

If you go with traditional logs, you'll actually need a drip to keep it lubricated. You could try the gore dripless packing. But I found that will leak and need adjustment as well. There are pros and cons to everything.

The mechanical seals are actually less tolerant to misalignment. There can't be any angular differences. Plus they have centering bearings also that will wear out if not correctly centered.

 

[Skybolt]

I put PSS in mine in 2014 when I bought the boat. Could not wait to get rid of the dripping old school stuffing box. I did consider replacing the packing with the newer Gore GFO type, but chose PSS. I did not check anything and just flat out replaced them. Boat went in the water and I didn't look back. No leaks and has been great ever since. The PSS are very very forgiving and do tolerate lateral miss alignment to a point. The shaft does need to be centered as Tom has pointed out.

They also need to be cleaned from time to time. I get short hauled yearly. When that happens, I also clean the metal face with 600 wet/dry. I do not touch the carbon face. The mechanical seal is dependent on both surfaces being clean and true.

@Rivertender what seal type do you have? Take a picture if you can. I also think replacing the existing seals is a mistake. You need to find someone that knows what they are doing. There are thousands of boat's that have these seals and have zero issues with them, aside from maintenance.

 

[Golfman25]

The mechanical seals are actually less tolerant to misalignment. There can't be any angular differences. Plus they have centering bearings also that will wear out if not correctly centered.

Well the manufacturers say differently.
Right from their website

“In addition, the carbon flange is over-bored to the shaft diameter allowing it to float around the shaft and thus compensate for most misalignment and vibration problems.”


https://www.shaftseal.com/

 

[Maybe A Dancer]

<SNIP>

They also need to be cleaned from time to time. I get short hauled yearly. When that happens, I also clean the metal face with 600 wet/dry. I do not touch the carbon face. The mechanical seal is dependent on both surfaces being clean and true.
<SNIP>

The importance of Skybolts statement cannot be overemphasized.

BEST !

RWS