Mike,
The reduction in vibration is very significant with electrics when repalcing low cyclinder count motors. Nothing smoother or quieter.
The boat I had was a race boat hard mounted engine (Toyota DOHC 6 cyl) with a hard mounted seats. I was always suprised to not feel motor vibration in that boat.
The shaft did have lateral loading as the skeg bush had some play. As it was a surface piercing prop/prop rider (3 point hydro) there must have been some loadings back along the shaft to the seal. The rubber hose that served as the mount for the seal housing could move a little with those loadings.
The boat often aired out and the prop would free rev and I have seen logs of the peak loadings when a prop goes from aired at WOT to submerged and the loadings can be extrordinary.
The silicon seals replaced nitrile rubber, which had replaced fibre packing. The previous two leaked, fibre was ok, nitrile lasted all of 5 minutes. In similar boats silicon were fine for a few seasons racing and the odd 111km race up the Hawkesbury at full speed. Grease nipples made sure the fitting was easy to grease. I am aware of boats ( with surdrives ie the seal out of the water) in which poor water cooling at the skeg resulted in shaft failures but those silcion seals seem to hang in there; they are also very cheap to try. However, I could do mine on a trailer, rather than a mooring which may make all the difference.
Andrew
Andrew:
It was just standard 1/4" packing in the boats original stuffing box. Holding up very well and there is much less leakage than with the old diesel. I think this because there is so much less vibration with EP. Thought about dripless shaft seal but, did not want to make too many changes at once when I converted to EP five years ago. I'm thinking it might not be a good idea anyway since I currently plan on electro sailing most of the time and there might be more wear on the dripless flange than normal. Also don't like that the rubber bellows is all that really holds back the sea f! rom entering the boat.
Capt. Mike
From: AJ Gilchrist <andrew@fastelectrics.com>
To: electricboats@yahoogroups.com
Sent: Sunday, July 22, 2012 10:19 AM
Subject: Re: [Electric Boats] Finally had to do some real maintenance!
Mike Nice report and pics
do you use packing in the stuffing box or seals?
I found the silicon rubber seals worked a treat in my hydro and stood up to high shaft rpm (7200) well
Andrew Gilchrist
On 22/07/2012 11:58 PM, Mike wrote:
Well, five years after the install I finally had to do some real maintenance on my Thoosa 9000 system beyond the annual oil change of the Honda 2000 generator. Like everything else my propulsion system I found working on it was so much easier than almost anything I had to do to maintain the old diesel engine. In this case it was replacing the shaft coupling:!
Capt. Mike
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