Sheaves for LM30 mast

[Argyller]

Hi,
I need to replace the sheaves at the mast top.
They are 50mm diameter, 13mm wide with a bore of 10mm.
All that are easily available are 8mm bore. Does anyone have a supplier?
The newer types have little solid at the centre, so I don't like the idea of boring out the 8mm hole.

Ron

[Brian & Glenda]

The mast on my 1983 LM32 was made by John Mast. You might try: shop.johnmast.dk/en/wheel-17/

Brian

[Sula]

{Oops! I thought I'd posted this last night - I see Brian and Glenda arrived at the same conclusion}

Could they be 50mm x 12mm x 10mm?

shop.johnmast.dk/en/wheel-17/hjul-oe50-x-12mm-hul-10mm-p28

shop.johnmast.dk/en/wheel-17/

(John Mast were probably the suppliers of the original mast.)

[Argyller]

Thanks for the advice, I found them on Jonmast, ø53mm x 13.5mm bore 10mm, an interesting size.

Moving on, I was unfortuantely not present when the boat was transported, and I'm now trying to re-rig the mast.
Could anyone possibly give me the which-rope-goes-where list for inside the mast?
I have main and genoa halyards, spinnaker halyard, but no topping lift.
Which halyard goes on the block that hangs of the front of the mast top?
Also, there's a small 6mm sheave on the front of the mast, just above the spreaders. Could that be for a spinnaker pole lift?
Apologies for all the questions, but years of Drascombes and the like, have left me woefully ignorant of things like hollow masts, wheels, heads, etc.

Thanks Ron

[Sula]

I'm no expert, but my understanding is -

• The block hanging off the front of the top of the mast is for the spinnaker halyard (because that has to be able to pivot from side to side).
• The block on the front of the mast, just above the spreaders, is for the spinnaker pole uphaul.
  
• The genoa halyard will come over a wheel in the front of the top of the mast (or lower down the mast in a fractional rig).  (The genoa halyard doesn't need to pivot from side to side, unlike the spinnaker halyard.)
• The main halyard will come out over a wheel at the top of the rear of the mast.
• The topping lift will come out over a wheel or block, also at the rear of the mast: sometimes just a twin to the main halyard wheel, sometimes a fitting further back in the mast crane (a fitting welded on top of the mast that extends it aft and (sometimes) forward).

You will have to decide for yourself which opening at the bottom of the mast you want each halyard to come out.  (I think the tradition is that the main halyard comes out on the starboard side, so you can reef while on starboard tack, which usually makes you the stand on vessel.) The main thing is not to have them twisted around one another inside the mast, and make best use of your winch(es).  On all three of the boats I've had with a spinnaker halyard, the fall of it (the non-sail end) has come down outside the mast.

I would normally expect there to be provision for a topping lift, but I recall that an LM26 I viewed had a (fixed?) boom strut to hold up the boom, so perhaps the LM 26, 28, 30 series we're fitted like this as standard, and had no topping lift.

 

[Charles]

When I had a boom strut fitted as part of a single-line reefing system I was still advised to fit a topping lift to take the weight of the boom and preserve the boom strut's seals, so I did.
Charles

[Sula]

Sept 22, 2018 20:50:15 GMT Charles said:

When I had a boom strut fitted as part of a single-line reefing system I was still advised to fit a topping lift to take the weight of the boom and preserve the boom strut's seals, so I did.
Charles

Charles, I may be mistaken, but I thought the boom strut of the LM26 I saw was rigid - i.e. no seals (or adjustment), and no need for a topping lift.  

I did not inspect or consider it in any detail, but when the previous poster said he had no topping lift, I thought that might (or might not!) be an explanation.

The Barton Boomstrut, which has a pair of flexing GRP rods to support the boom (and hence no seals), might also not need a topping lift  

[Charles]

But ours is a Selden strut, John, and that clearly does have seals, hence the advice we were given.
Charles

[Brian & Glenda]

Our LM32 has six lines exiting the mast. Three to port, three to starboard. They are, in top to bottom order of the cam cleats in the cockpit:

To Port:
- Spinaker Halyard
- Main Sheets
- Genoa Halyard

To Starboard:
- Reefing Line (One line, spits into two at mast, one rises up from boom and along the luff of the sail, and one runs aft along the boom then through a turning block where the aft reefing line continues along the leech, both with quick release clips to allow easy clipping onto either the single or double reefing cringles of the mainsail.)
- Main halyard
- Whisker Pole Uphaul. (This last line is labelled as Topping Lift, but as I have a fixed length boom strut to hold the boom off the pilothouse roof I don't need, nor do I have a topping lift. Some folks might call this a spinaker pole. I don't have a spinnaker, but I do use the pole to pole out my genoa on downwind runs, so this pole and its line line come in very handy on occasion.)

If you need to know the order of the lines as they exit the mast, I'll have to go down to the boat to have a look. Let me know if you desire that info.

(I also have a Harken traveller with an endless loop line control, that runs the width of my pilothouse cabin top. It allows reasonable control of the twist in the leech of the mainsail. My genoa is roller reefed, and the control line for that runs through pad eyes, down the port side deck.) That's the extent of my sail controls. No adjustable back stays or shrouds.

Brian.