Servicing the top of the mast

[MagicalArmchair]

So the mast is down, soon to go back up. I have a new LED masthead tricolour still to fit, and I am considering getting a Echomax radar target enhancer as we intend to zip across the channel when the kiddies are a little older.

Questions:

• Is there space to fit the Echomax target enhancer on the top of the mast? Is it packaged with a bracket?
• If I undo the nylock nuts, can I service the sheaves to make pulling the main up easier (its a good work out for the 1st mate (wife) right now mind you)? Or would it be best just to spray some silicon lube down it and work it back and forth?
• I get rather a lot of water in the cabin that runs down the mast. I can accept a bit, but it would be good plugging the top of the mast as much as I can to stop water getting in that way. Any tips for this or experience?

Top of mast:

Side of the top:

Wiring 'ole:

 

[merlin3688]

Sorry don;t know about fitting another bracket on the top. The masthead box can be taken out of the mast by undoing the two angled bolts at the top, this would make it easier to check sheaves etc. Sealing the mast at the top would work if your halyards are external, picture looks like they may be, if internal then you need to seal below the bottom exit, if you take the masthead out you could cut a foam shape to fit inside the mast, mastic to seal the edges and this will stop water running down the mast. If you have a conduit for wiring you may also find water in running down that.

 

[rob2]

Whilst the mast is down strip, clean and relubricate everything you can - you'll regret it later if you don't, just a missed opportunity. Ease the halyards so that you can slip a line through them and hold them at the mast head. Take off the locking rings and gently tap the pivot pins out of the mast. Clean the pins and sheaves, relubricate the pins and refit. In fact clean and grease everything you can find!

There is a maximum angle you are allowed to obstruct within the arcs of your navigation lights (see the collicion regs) so you should calculate the angle subtended by the diameter of the RTE. I believe the bracket used is the Glomex TV antenna mounting, so it's a fixed length. If the length is sufficient to achieve an obstruction of less than the allowance then you're OK. Otherwise the question is - what is the next highest available mounting point? Even mounting the RTE antenna on the pushpit will give you an acceptable range until the waves are big enough to shadow it.

As to sealing against leaks, the halyards are internal so you need to make arrangements below their exit from the mast, but beware that you should provide a drain if you block the mast, so that water doesn't pool within it and corrode something.

Rob.

 

[William_H]

It seems to me from the pictures that a plate across the top of the mast would stop much of the rain which gets down where the halyards turn on top sheaves. A bit of thin aluminium with necessary cut outs could be fitted if you removed all the bits on top of the mast and refitted them through the plate. Make a hump in the plate if you need more clearance for halyards. good luck olewill

 

[EdWingfield]

Whilst accessible have a careful look at the vhf aerial. You might save some tears later.

 

[MagicalArmchair]

Whilst the mast is down strip, clean and relubricate everything you can ...

There is a maximum angle you are allowed to obstruct within the arcs of your navigation lights (see the collicion regs) so you should calculate the angle subtended by the diameter of the RTE...

As to sealing against leaks, the halyards are internal so you need to make arrangements below their exit from the mast, but beware that you should provide a drain if you block the mast...

Rob.

Thanks all,

• I will strip it all down and grease the whole lot up.
• I must say I hadn't considered the obstruction to the new nav lights, anyone else mounted a sea-me or RTE on the mast top next to nav lights like this?
  
  edit: I found this: "All-round lights shall be so located as not to be obscured by masts, topmasts or structures within angular sectors of more than 6 degrees, except anchor lights, which need not be placed at an impracticable height above the hull."
  
  edit 2: So it would be nearly 12-15 degrees blocked the rough diagram below, ho hum.
  
  
  
  
  
  
• I am worried water will corrode the aluminium from the inside if I were to fill the mast with closed cell foam. Is there a gland you can buy to go in the mast at deck level? What are others experiences of sealing keel stepped masts?

 

[doug748]

I would fit a light plate, as already suggested, my mast top is closed.
If you have any spare exits for halyards near the top of the mast run a spare halyard into them, or close them off, they ship a remarkable amount of rainwater.

I am thinking of fitting a transponder at some stage and would site it on the pushpit. On a boat that excels to windward keeping weight off the mast is always worth doing.

Never tried closing off the mast and drilling drain holes. I suspect that getting it just right would not be easy with mast wiring, tricky internal profile and the difficulty of working 6 or 7 foot inside the mast with little access. If you have a go let us know how it works out.
I just put up with it and pump the bilge.

 

[Plevier]

Our 2008 Selden mast has a baffle in it, probably of foam, just above the deck boot below the halyard exits and there is a drain hole about 1/4" each side of the mast level with the top of the baffle. I think this is standard.
A bit of water still gets down it, maybe round the cables.

 

[MagicalArmchair]

I suppose the light aluminium plate would go over the top of the current set up as below?

And if I fit a stand off bracket for the RTE, I should get under the six degrees stipulated by colregs, so that is ONE option to keep it at the top of the mast I suppose...

I fear you are right re sealing the mast at deck level. I think I will leave it alone and just mop up.

 

[doug748]

I don't think I would be tempted to try and cover the lot and would not go under the L bolts that hold the box on the mast.

So very much what you have shown for the forward part but an arrow shape with a bulge on the side to go under the Windex shoe. That way you can always remove it easily at any time, just in case it caused problems with the halyard sheaves. I would not take off the pop rivets for the same reason.

Just my take on the thing.

 

[MagicalArmchair]

I don't think I would be tempted to try and cover the lot and would not go under the L bolts that hold the box on the mast.....

Good thinking Doug, if I ever need to get under there it should be easy to remove. It would also be easier to fabricate, fit, and cheaper to boot. Something like the below held on with four small self tappers where the dots are and then seal up the wiring hole with sikaflex? Clearly its not going to keep all the wet stuff out, but it may help.

 

[MagicalArmchair]

On the RTE, I have been chatting back and forth with Echomax about mounting on the top of the mast:

Their comment was:

I attach the operation manual which contains a drawing of suggested mounting options base on customer feed back as not all users chose the mast mount option due to the far horizon this gives.

"horizon (not response) 4 - 6 miles" Now what on earth does that translate to? If a ship can only see you at 4-6 miles, that's about 9 minutes till you are run down, or am I misunderstanding? What would be the draw back from having a far horizon?

 

[MagicalArmchair]

Mast service day yesterday! Took the mast cap off, removed the main halyard sheave, and this is what I found has been bodged up as a pin, about 30% worn through! (and this is the Halyard I would have used to go up in the bosuns chair :-s)

I doesn't even fit correctly:

You can just about make out the sheave the other side of the aluminium sheave in the picture above. The aluminium sheaves barrel (that appears threaded??) runs into the sheave behind to act as the pin for that sheave.

Do I need a threaded pin to go in the threaded barrel of the ally sheave? Do I just replace the sheaves entirely?

 

[prv]

Do I need a threaded pin to go in the threaded barrel of the ally sheave?

I suspect the "threading" is just a wear pattern from the bodged bolt. Can't see why the normal axle would be threaded.

For a similar job on Ariam's mast I bought a length of stainless rod from eBay, and secured it in place with a washer and a split-pin through a drilled hole at each end.

Pete

 

[Owl]

No wonder it was a workout getting the sail up!

Presumably you've got a ally sheave with a fixed bore insert of some kind? Looks like a thin stainless liner in the bore.

If the bore is stainless then you don't want a stainless pin as it will bind. I'm sure there are optimal choices for the bearing surfaces but I'd use brass as it would be ok, is easy to get hold of and easy to work with. Happy to be told otherwise!

If ease of raising sail is important then I'd investigate the cost of a replacement ball-bearing sheave.

 

[prv]

If the bore is stainless then you don't want a stainless pin as it will bind. I'm sure there are optimal choices for the bearing surfaces but I'd use brass as it would be ok, is easy to get hold of and easy to work with.

Hmm, possibly a good point. My sheaves were some kind of plastic (acetal?) running directly on the pin, so no such issues to worry about.

Would brass be strong enough, though?

Pete

 

[Owl]

Would brass be strong enough, though?

Stronger than an ally or acetal sheave, plus the load should (mostly) be in shear so I think it would be fine.

I think you would get an interesting wear pattern from the 'screw threads' on the inside of the sheave, but this shouldn't matter much.

 

[BabaYaga]

Do I just replace the sheaves entirely?

Yes. This looks like an old Seldén mast. They stock replacement sheaves in various sizes, now all made from some composite. Sits on plain stainless steel pins.
Never heard of ball bearings in this context, doubt it would be a good idea.

 

[Supine Being]

"horizon (not response) 4 - 6 miles" Now what on earth does that translate to? If a ship can only see you at 4-6 miles, that's about 9 minutes till you are run down, or am I misunderstanding? What would be the draw back from having a far horizon?

It depends whether you want to use the alarm function. It you mount it at the top of the mast, it's obviously going to get painted a lot more, especially in busy areas. Many of those vessels won't trouble you so you might not want an alarm going off all the time. If you want to use it as an alert to wake you if you're cat-napping on a long passage in open seas, then you might want to mount it lower.

If your only objective is to make sure that you are enhanced on radar for other vessels, then go ahead and mount it high.

 

[MagicalArmchair]

If your only objective is to make sure that you are enhanced on radar for other vessels, then go ahead and mount it high.

Thanks Supine, that makes lots of sense. If I can part with the beer credits, I might get on with it and mount it up high. I have AIS for a proximity alarm.

And thanks everyone for your take on my sheaves. I think I'll get them replaced with something less likely to cag up as PRV has and as BabaYoga suggests - time to talk to Selden I guess. I found some better photos:

Mast cap off:

Two sheaves parted:

Sheave together:

What do I ask Selden for? Two sheaves and a pin?