Reefing lines to cockpit - mast base blocks.

[ithet]

I am in the process of bringing the reefing lines (just clew at present, will probably add tack lines later) back to the cockpit. My yacht (Moody 28) already had some lines led aft from new, so updating the clutches and organisers was not a problem. However I am after advice on positioning the mast base blocks. Is there an optimum geometry for these? I would imagine if too far from the centre line there would be a difference in length (and therefore load) on each gybe when running. But putting them close behind the mast could clash with the kicking strap. Does this matter? Anything else to consider?

Barton suggest not using double blocks but I have seen these used so wondered if they were OK. Finally what if any is the best fixing, U bolts or bolted through pad-eye? There are no fixings on the mast base, the halyards come out of sheaves at the bottom.

Thanks in anticipation.

 

[bitbaltic]

If you are bringing back tack and clew lines then I guess you are slab reefing rather than single line. I'd first of all ask whether it's worth having six lines lead back, two of which need winching each time you reef in and all of which you need to remember to let off when you shake out, when instead you could lead a clew line for each reef to a winch and cleat(s) at the mast and just go forward to wind it in when pulling down the tack. Supposing you've considered this I agree that it will be very crowded at the foot of the mast especially if you have spinnaker lines and so on led back so definitely an issue. Sorry I'm not more helpful but look forward to the replies!

Cheers

 

[simonfraser]

I am in the process of bringing the reefing lines (just clew at present, will probably add tack lines later) back to the cockpit. My yacht (Moody 28) already had some lines led aft from new, so updating the clutches and organisers was not a problem. However I am after advice on positioning the mast base blocks. Is there an optimum geometry for these? I would imagine if too far from the centre line there would be a difference in length (and therefore load) on each gybe when running. But putting them close behind the mast could clash with the kicking strap. Does this matter? Anything else to consider?

Barton suggest not using double blocks but I have seen these used so wondered if they were OK. Finally what if any is the best fixing, U bolts or bolted through pad-eye? There are no fixings on the mast base, the halyards come out of sheaves at the bottom.

Thanks in anticipation.

You should have rope locks / catches at the mast end of your boom.
If you lock the reefing line with those you can let the deck clutch off and thus tacking / gybing won't put stress on the blocks at the bottom of the mast.

 

[MoodySabre]

I have done this on my Moody 31. There's an article (not mine) in the MOA Technical section. The tack lines are routed through bullseyes riveted to the mast a few inches below the gooseneck so that the tack is held in towards the mast. The position of the blocks at the foot the mast are not then crucial. My rigger said that Selden make an alternative to the ramshorns with just rings for the lines to pass through - could be the best idea if you are rigging three reefs. If I think a third might be needed on a passage then I rig one of the pair of reefing lines to the third reef (I made the first reef lines long enough) and just use the ramshorn and the outhaul to achieve the first reef. Very nice to be able to reef from the cockpit without the potential drawbacks of single line reefing.

 

[ithet]

MoodySabre,

Yes I have seen the MOA articles, and they have proved very useful. However, it is the positioning of the blocks for the clew pennants where they come down from the gooseneck and get led to the deck organisers that I am concerned about.

 

[Phoenix of Hamble]

I'm just doing the same job.... i'm fitting the Barton mast base organiser, which takes 4 blocks http://www.force4.co.uk/9472/Barton-Mast-Base-Organiser.html.... and avoiding the positioning being too critical by doing exactly what MoodySabre has suggested, other than i'm not using bullseyes, but instead a halyard diverter as the friction is a bit lower. It will cost you an extra few quid max, but will make life a lot simpler!

 

[MoodySabre]

MoodySabre,

Yes I have seen the MOA articles, and they have proved very useful. However, it is the positioning of the blocks for the clew pennants where they come down from the gooseneck and get led to the deck organisers that I am concerned about.

The blocks at the foot of the mast are away from the mast about the same distance as is the end of boom where they come out. They are shackled to the fitting at the foot of the mast and move to the correct position as the boom swings. I can only see there being a problem if the blocks were fixed.

 

[knuterikt]

I am in the process of bringing the reefing lines (just clew at present, will probably add tack lines later) back to the cockpit. My yacht (Moody 28) already had some lines led aft from new, so updating the clutches and organisers was not a problem. However I am after advice on positioning the mast base blocks. Is there an optimum geometry for these? I would imagine if too far from the centre line there would be a difference in length (and therefore load) on each gybe when running. But putting them close behind the mast could clash with the kicking strap. Does this matter? Anything else to consider?

I have been through this process, some tips to share.
It's easy to test the effect of different location for the mast base blocks.
With a helper holding a block i position (or if you have usable attachment points tie the block in place) and a rope threaded the whole "route" you can swing the boom and;
-Test for interference with other ropes and stuff (kicking strap).
-Measure the real effect of the changing geometry.

Use masking tape or insulating tape to make temporary marks on the rope - make it easier to see the change.

On my boat the mast ring have attachment points aft of the mast close to the kicking strap, no problem there. But testing before you start drilling is the best.

The tack reef lines go from the sail through check block on the side of the mast down to blocks sitting on the deck ring on the side of the mast.
The reef eye on the sail is close to the luff - so no noticeable change in geometry here.

Barton suggest not using double blocks but I have seen these used so wondered if they were OK. Finally what if any is the best fixing, U bolts or bolted through pad-eye? There are no fixings on the mast base, the halyards come out of sheaves at the bottom.

Thanks in anticipation.

You can use double blocks - just consider what lines you pair in the double block..
If you pair lines that will not be loaded at the same time it would work fine, lines that are loaded at the same time can give unwanted geometry issues (assuming the block is alowed to adjust).
-Main out haul + second clew ref = Ok
-First clew reef + third clew = Ok
-Main Halyard + Genoa (or spinnaker) halyard = Not so good.

But again - testing geometry on the boat is the best way to check for fair lead

Here you can see on the mast from top (port side)
1) Cheek block for second tack reef
2) Eye - The cunningham is attached the eye on starboard side.
3) Cheek block for cunningham
The check block for first and third tack reef is on the opposite side (starboard side)

At the boom you can see the clew reef lines going down almost parallel to the mast (side ways) a small angle towards the mast ring (=pivot point of the boom)
The bungee cord is there to prevent the in boom jammers from engaging (kind of beets the purpose using these - on my new boom it's not even fitted)

 

[ithet]

Thanks for the help so far. I think I shall try double blocks. Do not have enough room for the barton base fitting so still looking for advice on eye mountings.

 

[Phoenix of Hamble]

bear in mind that a double block with only one pulley loaded isn't as strong as a single.... personally, i'd go for singles.

 

[knuterikt]

Thanks for the help so far. I think I shall try double blocks. Do not have enough room for the barton base fitting so still looking for advice on eye mountings.

It's difficult to make specific advice with limited information.

I would start with calculating the expected load on the clew reef line.
The tack reef has far less load.

use this calculator http://www.harken.com/MainsheetLoading/
Use X=0 as we are looking for the load on reefing line (not main sheet)
Use sail measures corresponding to the reefed sail size, Wind speed = max expected wind with given reef.

If your clew reef has a traditional setup with the line going from the boom through the reef cringle back to the boom and through a sheave and forward...
The load on the the reef line is 1/2 the calculated value.

The load on the mast base block is reef line load * 1,41 (beacause the turning angle is 90°

I prefer using hardware that have a rated load. Wichard http://www.wichard.com/english.html have lot of different options.

You have to look find blocks and attachments that match each other - using bases with springs prevent the blocks from falling over.when unloaded .
Barton have "Stand up" blocks that could do the job (other makes have similar solutions).

 

[William_H]

I can see OPs probelm of the length of the outhaul and reefing lines varying with boom swing port or starboard unless the bottom turning block is exactly on centre line.
One option I have used is to make the boom vang 2 sided mounted so there is a gap in the middle for a double or even tripple block for turning towrds the winches. A kind of horse or saddle of ss wire could also bring the vang to centre at a point above and aft of the turning blocks.
An alternative is to use a large SS ring mounted under the boom on the middle of the back of the mast about half way btween gooseneck and deck which can direct the lines firstly to centre line under boom then allow some diversion to one side as you wish. A dead eye would cope with one line only being too small for more than one.
I disagree with the poster who advocated clutches to take the load after tensioning from cabin top winches. The whole idea of reefing et frokm the cockpit is so you don't need to leave the cockpit. good luck olewill

 

[knuterikt]

The numbers

I can see OPs probelm of the length of the outhaul and reefing lines varying with boom swing port or starboard unless the bottom turning block is exactly on centre line.

There are enough practical issues to sort out, but it's more fun creating those that don't exist

I "ordered" my brother who cruising our boat now to take some measures for me.

Swinging the boom from center line to port (starboard tack) until the boom touched the shrouds. almost 90° (we have straight spreaders).
Measuring on the port reefing lines (Clew) could not measure any change in length (open clutches)

Swinging the boom to starboard side (port tack) until boom touching shrouds.
Measuring on the same two lines (port) - 1 cm increase in length, mostly caused by the rigid boom vang.

Some comments to these figures
-We never let the boom that far out while sailing
-With a normal clew reef setup you have a 1:2 gain so 1 cm = 0.5 cm at the clew
-Most racers can adjust the outhaul from cockpit - do these get adjusted at each tack?

 

[ithet]

Thanks for usefull info

I can see OPs probelm of the length of the outhaul and reefing lines varying with boom swing port or starboard unless the bottom turning block is exactly on centre line.

There are enough practical issues to sort out, but it's more fun creating those that don't exist

I "ordered" my brother who cruising our boat now to take some measures for me.

This is exactly what I was trying to find out -does it matter about the offset blocks! Thanks knuterikt and brother, that gives me some parameters to work with, I shall try to measure the difference at the clutches before fitting. According to your earlier calculater I need blocks to manage about 250lbs, not a great deal.

Having fitted good clutches I would not be using the boom jammers!

Regards

 

[ithet]

Still looking for advice as to how best to mount blocks to deck - do not have room for the Barton fitting.

Thanks

 

[MoodySabre]

Isn't there room to rivet a fitting to the bottom of the mast? A photo of the mast base would help (couldn't find one on the MOA website.

 

[ithet]

Picture

MoodySabre,

Don't have one of mine, but here is very similar off anotherr boat. I have replaced the organisers (out of shot) with double stacked 3+3. The kicker goes to the fitting below the winch. The kicker would get in the way of a block on the ring on the mast base. I am hoping to leave the old winch in place for now, but that might not be possible.

Picture of Similar boat:
http://cdn.boatshed.com/autoimage-43243_BoatPic_MastBase.jpg

 

[MoodySabre]

That's similar to mine except that my lines come out of the mast at a wider angle.

I had the winch moved on to the side of the mast so that the genoa halyard comes up through a jammer and I can use the winch to crank it up.

My blocks are on a shackle below the kicker fixing. Because the lines come down straight they don't foul the kicker.

Not going to the boat until the end of the week so can't post a pic.

 

[William_H]

Attaching pulleys to deck. I just fitted a saddle to take the pulley with 2 bolts through to nuts and penny washers on the under side. 4mm in my case but a smaller boat. thqat way they can be further from the mast if necessary. Interesting results on reefing line length change by knuterikt I admit I was just going on what I thought would happen. But surely this would depend on how far off centre the deck turning block is and how far aft of gooseneck pivot the rope comes out. good luck olewill

 

[knuterikt]

Attaching pulleys to deck. I just fitted a saddle to take the pulley with 2 bolts through to nuts and penny washers on the under side. 4mm in my case but a smaller boat. thqat way they can be further from the mast if necessary.

Yes, as he has also calculated the expected loads he can size the fastenings appropriately.

Interesting results on reefing line length change by knuterikt I admit I was just going on what I thought would happen. But surely this would depend on how far off centre the deck turning block is and how far aft of gooseneck pivot the rope comes out. good luck olewill

Lots of variables that affects the result (with regards to change of length while pivoting), that's why testing different alternatives on the boat before drilling holes is a good idea.