RE: [campernicholson] Hydraulic Drives
We recently took out boat from Falmouth to Largs and, as luck would have it, after rounding Lands End we had very little wind and ended up motoring for 60 out of the total 72 hours. As a result when we arrived at Largs our Hydraulic Tank was indicating that it needed a little top up. The manual indicated that the correct fluid was Shell Tellus 32. I contacted Shell who said that they had not made that for some years; after some research they came back and said the correct modern equivalent was Shell Tellus S2M68. Apparantly, the S2M bit is important because there is more than one variant of Tellus 68 and this is the marine version.
The bad news is that it only comes in 20L drums at approx UKP 45.00 per drum.
Hope this helps.
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of John Stothart
Sent: 01 October 2013 19:03
Subject: Re: [campernicholson] Hydraulic Drives
I have a diagram of the hydraulic system from my original Nich 35 Green Book but it's in Devon and I'm in Mallorca until Sunday. I will look it out when I get home.
On 1 Oct 2013, at 19:13, <gall.john.j@...> wrote:
I recently had some hoses replaced on the hydraulic drive - the two leading to/from the dennison unit.
Now, I seem to have lost low end power in the system. Before the replacement, the prop would immediately bite, and provide decent acceleration. Well, some acceleration. Now, the "bite" is gone, and it seems like the system takes a while to get to 5 knots - whereas before it would get there almost immediately.
I've got the yard checking on the ISO on the fluid they used - I seem to recall that the system used to be run with an ISO 68 weight oil.
Is it at all possible that they connected the hoses reversed as to how they should have been installed ? I don't know, but presume different lengths of hose would almost make this impossible. Also, I don't know how the system is constructed - but it seems that the shift simply runs a multi-position valve tha t directs the fluid either clockwise or counter clockwise through the system - and that the impeller on the drive unit is tuned to operate in forward gear - and would sacrifice some in reverse. if the hoses were reversed, it would lead to poor forward speed.
If anyone has thoughts on this, it'd be appreciated.