My boat "Chivalry II", is 1981 33' Hunter with Datamarine instruments. The speed transducer is located in the bilge. My question is, what is the procedure for removing the tranducer to check the wheel? By the way, I do have the blug to use when it is removed. I am just not sure about the process. There is a ring connected to a pin which locks the transducer while it is in the thru hull hole. Is there a way the transducer needs to line up in the hole while replacing it, and does the temporary plug have special way to insert it? How much in comming water am I to expect when I pull the Transducer before inserting the temporay plug? Thanks for any help you can provide.
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Tim Leighton
NO BIG DEAL
Mike: I have an '85 H31 with a knotmeter impeller located in a small well (approx 1 1/2" dee) abeam the head. I pull my impeller plug often and have a pretty good system worked out. I really am not familiar with your layout, but mine is a "worst case" scenario with such a shallow bilge area. First of all, I get the impeller plug ready for removal (mine is a simple "screw on" bezel) and place the dummy plug next to it. I then place a large bathtowel over the site (keeps the "flood" confined mostly to that bilge area). Then, placing my hands under the towel (yes, you are blind, but better that than totally wet!), pull the old plug and insert the dummy as quickly as possible. I estimate I ship around a pint of water every time I do this and most of that stays in the bilge area with help of the towel. After cleaning and reassembly of the impeller, I simply reverse the process. If your set-up is in a deeper bilge area, you could probably do away with the towel. Trust me, you won't sink the boat!!!! (OK, I had some MAJOR concerns the first time I did this...all unfounded). FYI, I usually remove the impeller plug at the end of every cruise to help prevent growth on the impeller. Whole process only takes a few minutes. Good luck and happy sailing! Tim L. (S/V "TIDE")
Mike: I have an '85 H31 with a knotmeter impeller located in a small well (approx 1 1/2" dee) abeam the head. I pull my impeller plug often and have a pretty good system worked out. I really am not familiar with your layout, but mine is a "worst case" scenario with such a shallow bilge area. First of all, I get the impeller plug ready for removal (mine is a simple "screw on" bezel) and place the dummy plug next to it. I then place a large bathtowel over the site (keeps the "flood" confined mostly to that bilge area). Then, placing my hands under the towel (yes, you are blind, but better that than totally wet!), pull the old plug and insert the dummy as quickly as possible. I estimate I ship around a pint of water every time I do this and most of that stays in the bilge area with help of the towel. After cleaning and reassembly of the impeller, I simply reverse the process. If your set-up is in a deeper bilge area, you could probably do away with the towel. Trust me, you won't sink the boat!!!! (OK, I had some MAJOR concerns the first time I did this...all unfounded). FYI, I usually remove the impeller plug at the end of every cruise to help prevent growth on the impeller. Whole process only takes a few minutes. Good luck and happy sailing! Tim L. (S/V "TIDE")
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Bill Thiers
ditto No Big Deal
Before I pulled did it the first time, I had nightmare visions of an Old Faithful spewing out of the thru hull, sinking my boat. After using the towel technique just to try it, I thought about it and realized: the water pressure less than a foot below the surface of the water ain't much. A fast switcheroo with parts ready to swap makes it a little water to sop up.
Before I pulled did it the first time, I had nightmare visions of an Old Faithful spewing out of the thru hull, sinking my boat. After using the towel technique just to try it, I thought about it and realized: the water pressure less than a foot below the surface of the water ain't much. A fast switcheroo with parts ready to swap makes it a little water to sop up.
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J. McCue
Are they necessary anymore?J
I have a knotlog thruhull in my 28.5. I had same apprehension and visions of floods as I could only get one arm into that forward area to make the switch. It turned out less difficult than visioned. But since bought a GPS, I find I have no real need for this impeller etc thruhull. I haven't used it in 5 years. I probably should change the o-rings soon, but that's about it. Any other posts feel the same? Jim McCue
I have a knotlog thruhull in my 28.5. I had same apprehension and visions of floods as I could only get one arm into that forward area to make the switch. It turned out less difficult than visioned. But since bought a GPS, I find I have no real need for this impeller etc thruhull. I haven't used it in 5 years. I probably should change the o-rings soon, but that's about it. Any other posts feel the same? Jim McCue
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Mike Dumont
GPS vs Knot Meter
The major difference between the knot meter and the GPS speed on the water vs speed over ground. The knot meter gives you a consistent perfomance measurement for sailtrim without the variances of water currents. The GPS takes everything into consideration. Obviously, the current will help you when you are sailing with it rather than against it. It is sometimes nice to know that the speed you are going is due to sail trim alone. Both are nice methods of measurement as long as one understands the difference.
The major difference between the knot meter and the GPS speed on the water vs speed over ground. The knot meter gives you a consistent perfomance measurement for sailtrim without the variances of water currents. The GPS takes everything into consideration. Obviously, the current will help you when you are sailing with it rather than against it. It is sometimes nice to know that the speed you are going is due to sail trim alone. Both are nice methods of measurement as long as one understands the difference.
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J. McCue
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Tim McCarty
Contact Datamarine via website...
Mike, I recently replaced my old Corinthian knotmeter with the retrofit DCS100. I would contact Datamarine for the plug (you definitely need it, and, it surely can't be that expensive). With the plug, you simply unscrew the old ring, and (you need to be quick)remove the impeller with one hand, while shoving the plug into the hole with the other. If your quick enough, you'll get maybe a gallon of water into the bilge. Also, the impeller unit should have an arrow that you should point forward, so that that the impeller works properly. I would try to get the plug OR possibly borrow a plug from someone who has Datamarine instruments. Hope this helps...
Mike, I recently replaced my old Corinthian knotmeter with the retrofit DCS100. I would contact Datamarine for the plug (you definitely need it, and, it surely can't be that expensive). With the plug, you simply unscrew the old ring, and (you need to be quick)remove the impeller with one hand, while shoving the plug into the hole with the other. If your quick enough, you'll get maybe a gallon of water into the bilge. Also, the impeller unit should have an arrow that you should point forward, so that that the impeller works properly. I would try to get the plug OR possibly borrow a plug from someone who has Datamarine instruments. Hope this helps...
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Mike Knight
Thanks for all the info re speed transducer
Tim I have a plug, so that's not a problem. It was just the knowledge of how to line up the transducer once I replaced it. I did contact Datamarine and they provided some good feedback. Thanks again to you all for your information. Good Sailing!
Tim I have a plug, so that's not a problem. It was just the knowledge of how to line up the transducer once I replaced it. I did contact Datamarine and they provided some good feedback. Thanks again to you all for your information. Good Sailing!
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