Log Impellar

[WayneS]

Am about to fit a new Log impellar (Paddle wheel type) and need a bit of advice.

My last one was fitted on the centre-line, just forward of the fin keel. I caanot put the new one here as it is too short for the hull thickness. This is a bit of a blessing as it's current position exposes it to damage from the inside so I am not too concerned. I am going to have to plug this old hole with chewing gum I suppose.

I have two positions in mind.

1.
In line with the front of the keel and about 1 foot to port of the centreline. The only issue I have here is that it is in an under-bunk storage locker so withdrawing it to clean will result in SWIMBO moaning cos things get wet....

2.
Still a foot or so to port of the centerline but this time towards the back of the keel, or even behind the keel. This way it can be in the engine compartment and I that is my domain so SWIMBO has no say.


Anyone got any advice?

Before everywone tells me taht I should change SWIMBO, trust me, I have the same concerns about water fountains so am just using HER as an excuse.....


Cheers

Wayne

 

[colvic]

Is this going to be your main speed indicator or a supplement to the GPS?

Our paddle wheel was fitted where it was out of the way, but this made it very difficult to remove and clean as ours always seemed to attarct those little clams. Worst still, when the fitting failed and left a 50mm hole in the hull I wasn't able to get to it easily to stop water pouring in without an extension pole to hold the extra large wooden peg in place.

Start ref-fitting next week and though I've bought a new fitting have decided to rely on just the GPS as I've decided to keep holes through the hull to a minimum.


Phil

 

[Skyva_2]

Forward of the keel is cleaner uninterrupted flow of water. Cant check from home but I suspect most logs are mounted forward.

Aft of the keel there is more turbulence and possibility of log misreading.
IMHO.

Keith

 

[vyv_cox]

Definitely not aft of the keel. I bought a boat with the log fitted here and it was utterly useless due to turbulence. Alongside the keel at the forward end should be OK after some calibration but there may be an effect due to the heel on different tacks.

 

[Thresher]

Aren't there electronic logs with no moving parts on the market? why would anyone install a paddlewheel rather than an electronic one?

Some good advice here could save me a lot of hassle, I was just about to buy one.

 

[gjeffery]

Failure of the through hull fitting is a worry. Can you tell us why it failed?

I have just fitted a log impeller. The fitting is made of polymer, bronze, which I would have preferred, does not seem to be an option. I contacted the supplier and asked why they instruct that the fitting should be bedded into silicon, rather than Sikaflex. They told me that silicon does not react with the polymer but other bedding compounds might. So I used silicon. My main worry, apart from leaking, would be failure of the plastic nut on the inside of the hull fitting. The suppliers also instruct that the fitting should be glassed in to the hull; that is reassuring and I hope will provide security if the fitting should fail. Incidently. I glassed the fitting in using the Plastic Padding filler that contains glass fibres.

I found this convenient to work with.

Regarding location. Too close to the front of the keel may be within a zone of stagnation. Too close to the rear of the keel would be in turbulence. The Silva website gives some good pointers on placing the transducer. They say not closer than 250mm to the fromt of the keel and not further than 750mm.

 

[dickh]

Re: Log Impellar - non moving type

I think EchoPilot do one that has no moving parts, but if I remember it's expensive - not sure but I seem to remember a figure of £500.

dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[Trevor_swfyc]

Re: Log Impellar - non moving type

Its is important to mount in an area free of turbulance, this means in front of the keels in most cases. One point to remember is to put it in a position so that haulage strops do not damage it. On my Mirage 27 I fitted a new paddle wheel log last season and mounted it port side in front of the forward bulk head, which was about 2ft in front of the bilge keels. The depth gauge is on the starboard side glassed in with no holes in the boat. The pilot hole is drilled first from inside and then the hole cutter from the outside. The saying measure twice cut once comes to mind.
Good luck
Trevor.