Where to site the log paddlewheel

[Equinox]

I was wondering where the best position it to cut the hole for a speedlog paddlewheel (NASA). I'd rather avoid having to cut the hole on the centreline as I feel this may cause a weakness when pitching and pounding and could perhaps lead to cracking.

I was planning on positioning it just off the centreline by the fin keel. It's only a 27 footer so there isin't too much room for'd as the toillet is for'd of the saloon and it's not possible to site it there. Any further forward than that and it would spend half the time out of the water in a seaway. Are there any obvious disadvantages to where I intend to position it, such as the turbulence from the fin keel causing a false reading?

Thanks in advance.

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[Evadne]

paddlewheel deja-vu

I'm sure someone asked this question less than a fortnight ago, and got a shed load of answers. I'd suggest you do a quick search for log impellers or paddlewheels.

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[Equinox]

Re: paddlewheel deja-vu

The search came up trumps. Thanks for the tip!

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[claymore]

Re: paddlewheel deja-vu

I haven't looked at the other posts so perhaps this has been suggested already and if so, apologies. Mount the blasted thing where you can reach it from your dinghy with a brush to give it a swipe when it decides it's done enough spinning and gets some weed or a barnacle on it

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Claymore
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[Evadne]

... or fit a trailing log!

NM

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[rex_seadog]

Re: paddlewheel deja-vu

Interesting idea, Claymore, but for mine I don't think this would be sufficient. Usually after a few days on the Dart my paddlewheel is clogged with slime, miscellaneous debris and even very tiny worms! (Down here we don't enjoy the luxury of clean Scottish water - except when made into Malt!) It then needs to be removed and meticulously cleaned with fine wire and tissues to ensure that it spins very freely.



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[qsiv]

Re: paddlewheel deja-vu

Just the reason that the new boat is having a solid state transducer, never stops working, always accurate

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[vyv_cox]

Advice given when buying a log transducer is to put it ahead of the keel, on the centreline. Putting it alongside the keel will have the effect that even after calibration, it will give a different reading on port and starboard tacks. Aft of the keel is definitely out as a stable reading cannot be achieved.

I don't believe that your concerns about strength reduction are justified (unless there's something wrong with your boat!) The majority of hulls are equipped in this way and putting a 2 inch hole through it will barely affect strength. If you remain unconvinced, why not add some layup and thicken up the intended area (I assume we are talking GRP?) before drilling the hole?

Access to the transducer is important as they need to be removed for cleaning on a regular basis. Putting the transducer inside a locker where you are leaning over it does not make the job of removal very easy.

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[charles_reed]

Ideally about midway between forefoot and keel on the centreline (where skin friction gives over to turbulence in the water flow).

However don't expect a paddlewheel log to be accurate - if you want accuracy go for a training log.

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[rex_seadog]

Re: paddlewheel deja-vu

Yes, qsiv, a solid state transducer with no moving parts would seem to be the answer. Echopilot have been producing one for several years but when I posed the question on this forum as to their reliability and accuracy no-one seemed to have any experience of them. I found this surprising considering how much hassle it is to keep a paddlewheel clean. Last time I looked they cost around £400, which I baulked at paying, but surely not prohibitive to many of our wealthier members who seem to spend a fortune on other electronic gizmos!

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