A while ago somebody was after one of these. Don't remember who. I took this one out of my boat today and I will be having the hole glassed in.
If anybody wants it (free), just PM me with name and address and I will send it.
I am going to let the GPS tell me how much fun I am having. 
Hi Cisco
It was I who you kindly sent your old unit to and requires the plug .
I have the same through hull fitting but no plug and it has always concerned me , it would be great to get such a plug and more than happy to reimburse you for your effort if you have a paypal it would be so easy 
Im about to fill mine in to Cisco .
Get enough speed input from Navronics and one less thing to go wrong
Feather the edges inside and out and fill with glass mat and resin. That is what my glass guy tells me.
Bit worried about this trend to rely only on SOG and ignore BWS when the comparison between the two is one of the best navigational planning tools.
Select to expand quotelydia said..
Bit worried about this trend to rely only on SOG and ignore BWS when the comparison between the two is one of the best navigational planning tools.
Im not going to rely on satellite completely either. Lydia, whats BWS?
Select to expand quotelydia said..
Bit worried about this trend to rely only on SOG and ignore BWS when the comparison between the two is one of the best navigational planning tools.
They are handy for detecting current or for racing and adjusting sail trim etc. The downside is l keeping the paddle wheels clean. I reckon it's two years since I even took the cover off mine. Commonsense and knowing how fast your boat really travels through the water in the conditions is probably enough for most people when using GPS.
BWS (or same systems use BSD) but boat water speed or speed through the water as opposed to speed over ground.
Difference on the east coast can be over 70 miles day if you are using this properly.
I don't use put the log in every time I sail but on a long passage I always put it in
Select to expand quotelydia said..
BWS (or same systems use BSD) but boat water speed or speed through the water as opposed to speed over ground.
Difference on the east coast can be over 70 miles day if you are using this properly.
I don't use put the log in every time I sail but on a long passage I always put it in
Couldn't agree more. I use mine when passage making and consider it very important. I pull it back out to keep it clean when I'm not using the boat. (the bung is not meant to roll around in the bottom of the hull gathering dust).
The log is also required by your wind instruments to determine "apparent wind"
The log is also required by your wind instruments to determine "apparent wind"
No,no,no a thousand times no. The true wind calc MUST be made from SOG.
You are at anchor, zero wind speed, 3 knot current by your paddle wheel. You vector add the paddle wheel speed to indicated wind speed to get true wind speed, answer 3 knots. False result. You vector add the speed over ground ( 0 ) to apparent wind speed and you get the correct answer - zero.
Sorry cisco, I'm just getting over the dreaded coughing disease and I have become a grumpy old man.
Select to expand quotePhoenixStar said..
The log is also required by your wind instruments to determine "apparent wind"
No,no,no a thousand times no. The true wind calc MUST be made from SOG.
You are at anchor, zero wind speed, 3 knot current by your paddle wheel. You vector add the paddle wheel speed to indicated wind speed to get true wind speed, answer 3 knots. False result. You vector add the speed over ground ( 0 ) to apparent wind speed and you get the correct answer - zero.
Sorry cisco, I'm just getting over the dreaded coughing disease and I have become a grumpy old man.
I think that one is arguable Phoenix. Say you have 8 knots true wind that is giving you 4 knots through the water but you are pushing directly into a 4 knot current. How would that one work out??
Considering my hull is only about 12 mm thick where I pulled the transducer out I am thinking I will put a bronze skin fitting blank in instead of having it glassed in. I pulled the old fitting out because the VDO Sumlog was buggered and I refuse to buy anything VDO due to their policy of not selling spare parts.
Putting a bronze blank in gives me the option of fitting another brand of log in at a later date. Paddle wheels are a constant source of bother but I believe there are other transducers that sense water flow non mechanically. Does anyone know of those and whether they need to be constantly cleaned??
Select to expand quotecisco said..PhoenixStar said..
The log is also required by your wind instruments to determine "apparent wind"
No,no,no a thousand times no. The true wind calc MUST be made from SOG.
You are at anchor, zero wind speed, 3 knot current by your paddle wheel. You vector add the paddle wheel speed to indicated wind speed to get true wind speed, answer 3 knots. False result. You vector add the speed over ground ( 0 ) to apparent wind speed and you get the correct answer - zero.
Sorry cisco, I'm just getting over the dreaded coughing disease and I have become a grumpy old man.
I think that one is arguable Phoenix. Say you have 8 knots true wind that is giving you 4 knots through the water but you are pushing directly into a 4 knot current. How would that one work out??
Considering my hull is only about 12 mm thick where I pulled the transducer out I am thinking I will put a bronze skin fitting blank in instead of having it glassed in. I pulled the old fitting out because the VDO Sumlog was buggered and I refuse to buy anything VDO due to their policy of not selling spare parts.
Putting a bronze blank in gives me the option of fitting another brand of log in at a later date. Paddle wheels are a constant source of bother but I believe there are other transducers that sense water flow non mechanically. Does anyone know of those and whether they need to be constantly cleaned??
Does not sound right Cisco. I would have thought your masthead wind instrument would measure "apparent wind" directly. Your computerised instruments would have to calculate True Wind, and SOG would be needed.
The masthead sensor measures Apparent wind. The Raymarine system calculates True wind, relative to the boat, based on Apparent Wind and speed through the water. There's no option (at least, in the ST60) for using SOG from a GPS instead - I seem to remember reading somewhere that this is due to the formal definition of the various NMEA parameters. I don't know what other manufacturers do.
I wouldn't be without a paddlewheel and the data it provides. I pull mine out and give it a coat of this stuff every couple of months:
www.whitworths.com.au/transducer-paint-92ml
It's all a matter of definitions. This version of True Wind, which has been around since pre GPS days, is "True" relative to the water surface, whether that is moving due to currents or not. It is calculated from Apparent speed and direction, with appropriate vector offset by speed through the water.
There's another parameter, which I believe is called "Ground wind", which as you might expect is relative to earth's surface. Calculating that would require SOG.
You could probably make a case for either option being the more useful under various circumstances. However, as currents rarely get over 2-3 knots, and wind is rarely of any relevance unless it's several times that, it's hairsplitting in my view.
This argument has been done to death long ago. See here for example:
www.cruisersforum.com/forums/f121/differences-between-ground-apparent-and-true-wind-direction-73563.html
Especially post #4.
fills a hole anyway
I've a belly full of wind at the moment
I guess that's true wind and Sog 
Select to expand quoteQLDCruiser said..
It's all a matter of definitions.
Good point, and readily explains the Raymarine 'effect'.
Although, as mentioned in the referenced thread, the consequence of the definition is this:
....If you are completely stationary at anchor in 100% dead calm, but a 5kt tidal current is present, your True Wind is now 5kt.
Which might surprise the intuition of your average old salt.
Select to expand quoteQLDCruiser said..
It's all a matter of definitions. This version of True Wind, which has been around since pre GPS days, is "True" relative to the water surface, whether that is moving due to currents or not. It is calculated from Apparent speed and direction, with appropriate vector offset by speed through the water.
There's another parameter, which I believe is called "Ground wind", which as you might expect is relative to earth's surface. Calculating that would require SOG.
You could probably make a case for either option being the more useful under various circumstances. However, as currents rarely get over 2-3 knots, and wind is rarely of any relevance unless it's several times that, it's hairsplitting in my view.
True wind is something of a misnomer in that it is shown relevant to the boats heading, as is apparent wind and is never dependent on current. If you know SOG you don't need to know about the interaction between boat speed through the water and current.
True wind is found by vector addition of SOG to Apparent wind and is shown as speed and direction relevant to the boat. And current is only relevant in that it affects SOG. If you need to know the current then you need a paddle wheel and GPS to do another vector addition.
I don't know why this is so confusing. It's just the way it is.
If we are using a wind instrument to achieve more efficient sailing, why would we be concerned with "True" wind speed and direction??
Surely if the boat is sailed to the best "Apparent" wind direction relative to the course we want, that is as good as it gets isn't it??
Select to expand quotecisco said..
If we are using a wind instrument to achieve more efficient sailing, why would we be concerned with "True" wind speed and direction??
Surely if the boat is sailed to the best "Apparent" wind direction relative to the course we want, that is as good as it gets isn't it??
You will end up chasing the AWA with boat speed changes.
Ok here's an attempt to clarify:
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"Pre-GPS TRUE WIND" = wind speed/dir when you totally disregard current.
You can calculate this from Apparent Wind and Boat Water Speed (this is how pre-GPS instruments do it). May give 'strange' answers when the boat is in calm conditions but current is flowing.
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"Post-GPS TRUE WIND" = also known as "GROUND WIND" = wind speed/dir when you factor in current.
You can calulate this from Apparent Wind and SOG. Never gives 'strange' answers. This is also the one used by weather forecasters.
Should add that, in conditions where wind speed is much higher than current speed (very often), the above two will be very good approximations of each other. So for most sailing conditions, the values will be very close.
