willtaylor
New member
From: willtaylor
Problem one:
My 20ft Signet is powered by a longshaft Honda 5. The motor is a delight except for a tendency to break
shear pins when changing into gear, especially reverse. Clearly this can be inconvenient, even dangerous. I
do throttle right back (indeed it is not possible to change gear on this motor unless you do). I also realise
that I could replace the brass shear pins with stainless steel. That would solve the problem but would
endanger the prop (and gears!) a shear pin is intended to safeguard. Has anyone solved this problem? Is
there an intermediate material between brass and ssteel that would add strength but retain some protection?
Given that the boat draws 3ft and the prop should not hit anything I would rather risk the steel pin than find
myself as I did yesterday needing to hoist sail on a (slightly) lee shore and falling tide having gon alongside to
drop visitors.
Problem two.
I have a new NASA Duet. The echo sounder seems to be fine. The speed and distance log has been
intermittent. Howevr we seemed to have freed it quite well and it is now recording realistic seeming speeds
and distance.
I also have a Garmin 12 GPS. They are both set for nautical units. There is quite a large discrepancy between
the speeds shown on the GPS and the log. I realise that speed through the water and over the ground are
different, and are affected by tidal drift, leeway and all sorts of variables. Even so I suspect the impeller
driven log to be under recording. My principal question therefore is - can I trust the speed shown by GPS? If
that is accurate then I have a benchmark and can proceed to check the impeller log against that.
I cannot see how the GPS can be inaccurate at showing speed over ground, but I am put into doubt by a
chance remark I remember when I first saw one in use when sailing across the Channel with a very much
more experienced friend. He said the speed shown by the GPSwas too fast. I didn't think about it at the time,
now I have doubts because of that seemingly irrational remark.
I shall appreciate any helpful suggestions.
Will Taylor
Problem one:
My 20ft Signet is powered by a longshaft Honda 5. The motor is a delight except for a tendency to break
shear pins when changing into gear, especially reverse. Clearly this can be inconvenient, even dangerous. I
do throttle right back (indeed it is not possible to change gear on this motor unless you do). I also realise
that I could replace the brass shear pins with stainless steel. That would solve the problem but would
endanger the prop (and gears!) a shear pin is intended to safeguard. Has anyone solved this problem? Is
there an intermediate material between brass and ssteel that would add strength but retain some protection?
Given that the boat draws 3ft and the prop should not hit anything I would rather risk the steel pin than find
myself as I did yesterday needing to hoist sail on a (slightly) lee shore and falling tide having gon alongside to
drop visitors.
Problem two.
I have a new NASA Duet. The echo sounder seems to be fine. The speed and distance log has been
intermittent. Howevr we seemed to have freed it quite well and it is now recording realistic seeming speeds
and distance.
I also have a Garmin 12 GPS. They are both set for nautical units. There is quite a large discrepancy between
the speeds shown on the GPS and the log. I realise that speed through the water and over the ground are
different, and are affected by tidal drift, leeway and all sorts of variables. Even so I suspect the impeller
driven log to be under recording. My principal question therefore is - can I trust the speed shown by GPS? If
that is accurate then I have a benchmark and can proceed to check the impeller log against that.
I cannot see how the GPS can be inaccurate at showing speed over ground, but I am put into doubt by a
chance remark I remember when I first saw one in use when sailing across the Channel with a very much
more experienced friend. He said the speed shown by the GPSwas too fast. I didn't think about it at the time,
now I have doubts because of that seemingly irrational remark.
I shall appreciate any helpful suggestions.
Will Taylor
