Masthead Anemometer Problem

Nick_Pam

Nick_Pam

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I have a slight problem with my masthead anemometer which I am hoping someone may be able to help me with.....
We went down to the boat two weekends ago, and at that time, the anemometer cups on my masthead unit were spinning merrily in a force 2/3, but last weekend, in a force 6, gusting 7, they seem to have suddenly stopped going round!!
Now I know that when we bought the boat, the ex-owner had to fix this exact same problem, but apparently all he did was to go up and "give it a knock and a spray of WD40"
My theory is that at 8 years old, the shaft on which it spins is worn, but until I pluck up the courage to have SWMBO hoist me up the mast, so that I can fetch it down, I won't know......
My questions are........
1. If this is the case, can it be repaired, or do I need to think about replacing it?
2. What can I expect to see when I get up there? (I've only owned the boat for a month and haven't been up there yet)
3. If I need to replace, do I need to identify the correct masthead-unit to go with the instruments fitted, or are they interchangeable?
4. Am I better paying "someone who knows" to do this, or is it within the scope of a reasonable DIY'er (alberit one with a poor head for heights!!)
Any helpful suggestions/ideas/comments would be gratefully received.
Regards
Nick

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<<I've only owned the boat for a month and haven't been up there yet>>

You need to get up there anyway to survey the masthead and check the condition of rigging, split pins, shackles etc. If you haven't already done so, a radio check is worthwhile before you go in case the VHF antenna needs attention.

Take a camera with you and spare bulbs for any masthead lights (probably a 10W and 25W for all-round and tricolour). Also pliers, screwdriver, tape, seizing wire, WD40. Take lots of pictures whilst there for future reference. Change the bulbs whilst aloft.

You will need to be able to get above the mast for all this, so will need to take a safety harness and some method of getting higher than the bosuns chair will take you. A pair of strops to attach to the masthead to stand in will do - this is when you need the harness. A bucket on a long line attached to the bosuns chair is the best way to pass things up from on deck.

Whilst there you can probably free the anenometer, but have a good look in case it's time for a replacement. Probably is if it's gone twice in a month. It will be instrument type dependent (not universal). Usually easy to replace as they are designed to come off when the mast is stored.

...and before you go up there use your binoculars to have a good look at what fittings you might need.

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by tome on 12/05/2004 11:51 (server time).</FONT></P>
 
I've had this problem a few times.

Maybe the best solution is go up and detach it, and bring it down to earth to have a play there. Working at height is difficult and uncomfortable. MHUs usually detach quite easily.

When mine stopped going round, both times it was degradation of the bearing. Once I managed to reprieve the bearing with WD40 and some gentle wiggling, the second time it had properly died, and had to be sent away to be replaced.

The data format of some MHUs is interchangeable between different manufacturers if they are sending standard NMEA, but in other cases it is not. What almost certainly won't be interchangeable between manufacturers are the connections, mounting and plug/socket. If you try to replace it with another manufacturer's MHU be prepared for extra bother like having to replace connectors on the cable and re-drill mountings, and maybe for it not to work anyway.

If you are happy to go right to the top of your mast, there is no need to call in someone. Get up there, get it off, have a play with it on deck, and if no joy send it back to the manufacturer for repair. You don't want to have to buy a new one if you can avoid it - apart from Nasa, the price of MHUs makes you eyes water more than two hours in a harness.

When you take it off, tape over the connector at the top of the mast with some insulating tape. You don't want water getting in if it takes a few weeks to repair.

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.
 
Hi,
I had the same problem with a Stowe MHU. Would intermittently decline to roatae in light airs until it stopped altogether. I was quoted £240 for a replacement from A.W.Marine (the only source of spares)!

Got the unit off and stripped it down to discover that the fault lay with a worn small ball race bearing which I replaced for the princely sum of £3!

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Well done with the £3 repair. I can not begin to list all the perfect cheap repairs I have done on "units Sir, it will cost XXX". our society is geared up on chucking things out. The only trouble is I tend to keep too much to use as spares or to find a good home! i can not get the car in the three car garage. help.!

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Tom

If you want to go up the mast to survey the fittings - you dont want to be hoisted up said mast - you want a crane, or a low tide and tall quay. Personally I only go up rigs I have confidence in!


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Quite agree - if in doubt use a crane.

However, I was quite confident in the main halyard and went up using a TopClimber with a safety harness, having first checked everything with binnos. Here's what I found:
Masthead1.jpg

The spinnaker halyard block was attached with a snap-shackle, and the top shackle was badly worn and wasn't wired. The forestay fitting was splayed out and the split pin was almost out! Could have lost the mast.

It didn't take much to fix everything, but I was very glad I'd inspected it.

BTW, the black wand visible is the windvane on a ST60. The camera was a v cheap digital one and I now use one with a macro facility which gives much better detail/focus.

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WOW!
Thanks all for the responses.....
At least I know that the rig is OK, as I forked out a load of dosh to get a full pre-purchase survey in March and I know for a fact that the surveyor went up the rig and pronounced it well rigged (and yes I trust the surveyor!)
Only issue I have is that my threshold for vertigo is about 100 feet (I know from climbing experience!) and the rig is not that high!
I've got a climber, a good main halyard, a good spinnaker halyard and a "lecky" winch for SWMBO, so it's up the rig for me...gulp!!!!
Nick

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Anything that needs a spray of WD40 to free off will quickly need some other form of maintenance. WD40 is great at freeing stuff, but useless as a long term lubricant (actually worse than useless, as it enables further damage to be done). A lubricant that is better than WD40 for freeing off, and also provides a short to medium term lubricant, I would recommend <A target="_blank" HREF=http://www.team-zx1.co.uk/>ZX1 C60.</A>

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Anything that needs a spray of WD40 to free off will quickly need some other form of maintenance. WD40 is great at freeing stuff, but useless as a long term lubricant (actually worse than useless, as it enables further damage to be done). A lubricant that is better than WD40 for freeing off, and also provides a short to medium term lubricant, I would recommend <A target="_blank" HREF=http://www.team-zx1.co.uk/>ZX1 C60.</A>

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I once repaired one of these by removing the egg cups, carefully freeing and lubricating the bearing and then refitting the egg cups. Then a trip back up the mast to refit. Worked a treat.

Ten minutes later, as we left the marina, heard an ominous "plop" from downwind. Nut had come loose and egg cups flew off! Next time, I'll use some bl**dy Locktight.

TonyD

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