Log?

[Haven't-a-Clue]

Ay oop, I want to measure my speed through the water (Merryfisher 625 wi' large o/b on back). I'd prefer NOT to drill 'oles in hull if poss, so what do I look for and what would it cost (v.short of readies)? I didn't want to put this on the backup plotters' thread, but it was there I noticed summat about Walker trailing logs and thought it might be an answer, 'till I saw comments about price! so probably no use to me. If it's any help, I would be using it mostly at low speeds (ie hull speed) 'cos I don't think it'd work on the plane......I could be wrong. Suggestions please. Ta everso.

 

[MarkGrubb]

There's normally 2 or 3 trailing logs on Ebay. Don't know what they go for as never bid, but the starting prices are normally a couple of quid (unless they are being sold as collectors items). I've seen a few complete with box and spare trailing impeller starting at £10. That's probably your best bet.

If you're really hard up you can make one: long piece of string, tie some knots in it and a log at the end and chuck it out the back every 15 minutes, say, to count the knots.

Not sure how long it needs to be and how long you should count the knots for, or how far apart they should be. You'll have to do the maths.

 

[Haven't-a-Clue]

OK, tried that, none on offer at the moment. Are they still sold new, if so, where should I look (tried google, either I'm entering the wrong search criteria - very likely! /forums/images/graemlins/blush.gif - or they're not available - find that difficult to believe /forums/images/graemlins/confused.gif) and what should I be asking for (to paraphrase Patsy from Ab-Fab) "names, darling, names"!! /forums/images/graemlins/grin.gif I am willing to spend money I haven't got (credit card) /forums/images/graemlins/tongue.gif, but not excessive amounts and, of course, only for the right thing. Am I asking for too much here, I don't know (probably am). /forums/images/graemlins/grin.gif

 

[Evadne]

As long as you are not after the ones with the bronze impeller you should be able to pick up a Walker log for £50, give or take. If you can fine a Stowe trailing log that works, it may be the same or less. And sorry, you can't have mine. /forums/images/graemlins/smile.gif

 

[MarkGrubb]

Sorry I should have been a bit more helpful. The most popular model was called the Walker Log (or manufactured by Walker, sor somthing like that), though there are others. Punch 'Walker Log' into the ebay search, there are three for sale at the moment. Cheapest is currently at £10. Other two are around £25.

 

[Gordonmc]

Wouldn't a cheapo fishfinder do the trick?
Most are transom mounted, so don't need impellor transducer holes in the hull. Hummingbird do speed-capable ffs and you get the added bonuses of depth and water temperature.

 

[dnickj]

most large o/b motors have a pick up tube on them all you need to do is buy the guage for the other end

 

[Eeyore]

I think you are referring to the "Knotmaster" log. Full name 'Thomas Walker Knotmaster Taffrail Log'

It was manufactured by Thomas Walker in the UK but is no longer made. There were, as far as I know, two basic versions....the KDO type and the upmarket one (whose initials I can't recall at this moment, think it may have been KDS). Both types came in wooden boxes complete with two spinners in the lid, two weights, instruction booklet, two fixing plates (port and starboard), the log head itself and the bracket. There should also be two trailing lines and an oil can!! The second version contained an additional 'dynamo' contraption which drove a seperate large speed dial, calibrated in knots.

If you can get a complete one on e-bay for £50, then you are doing well. They are sometimes sought after, particularly by Americans and are therefore usually expensive. I think the new price when last made was around the £350 -£400 mark. (I have both versions kicking around in my after cabin somewhere, both new, never used!!). Should you manage to get one, make sure the port & stbd fixing plates are there, they are sometimes hard to find.

See: http://www.robertwhite.com/cgi-local/sho...nav_bar=weather

 

[Tranona]

The big one was the Excelsior. They also towards the end of their life did a "cheapie" version which I have and is mounted in a stirrup lashed to the pushpit.

Would not recommend for an outboard powered boat. They are a pain to stream and inevitably you will pick up the line with your prop and at the very least lose the spinner. You also need a different spinner for more than 8 knots.

They were designed for long passages in slow boats where they are better than guess work - they don't all give you speed only distance run.

 

[barnaclephill]

A GPS is much cheaper, and comes in handy in other ways also. Although it measures speed only over the ground, if you reverse your track (direction) and average the 2 results, the speed would be that of the boat through the water.

 

[john_morris_uk]

Or grit your teeth and drill a hole through your hull like everyone else does. Not too sure why people suffer paranoia about through hull fittings. Tie a softwood tapered bung nearby and have a hammer on board (or use a winch handle!) if you are really worried about sinking. (You are MUCH more likely to sink through sudden grounding or being run down I suggest.

Millions of boats sail millions of miles with through hull logs...

 

[Evadne]

[ QUOTE ]
Millions of boats sail millions of miles with through hull logs...

[/ QUOTE ]

I agree, but when you sail hundreds (or less)in a season then fouling is more of an issue, and trailing logs don't suffer from fouling - unless you count hauling in when it picks up a bit of bladderwrack.

 

[john_morris_uk]

Or do what we do and put the blank 'dummy log' in when we are not on the boat? You will have to sponge out the litre or two of water that comes in when you swap them over, but its no great hardship.