Shroud / Spreader Attachment

[rajjes]

I am finally getting close to re-stepping the mast after replacing the rigging and have some question on how the shrouds should be attached to the spreader ends on the Proctor Mast of my 1980's Moody. I'm confused as the current setup seems to conflict with the general info found on the web:

1. Should the shroud be securely fixed to the spreader tip or not? - The spreader ends have a screw down clamp to prevent the shroud from jumping out but it does not clamp the wire tightly so with the old rigging it was still free to run.

2. Should the spreader lie perpendicular to the mast or angled slightly upward to bisect the angle? - The spreaders ends have some up/down play and can be angled upwards a few degrees however their bases seem to be made for a perpendicular fit?

Appreciate your help!

Duncan

 

[TimBennet]

They should bisect the angle (on single spreader boats).

The less they bisect the angle (because they are constrainer by their fittings) the more important it is to lock them securely at their outboard end. However if the angle is perfect, they still need constraining so there's no chance of coming out of their fitting when slack on the lee side. Fixing also stops them being dislodged when someone climbs the mast.

 

[Salty John]

+1 They should bisect the angle, they should be secured. Drooping spreaders are a to be avoided.

 

[rajjes]

Thanks both. The spreader ends have a screw down clamp however the wire is a loose fit in the clamp. I was thinking of wrapping the wire with amalgamating tape so the clamp can bite in it for securing?

 

[chasroberts]

I think you need the wires to be able to move a little so that when you tighten up you are not deforming the angle of the spreaders by dragging them downwards. The end clamps are there to stop the shrouds 'jumping out' as mentioned above so do not need to be clamped tight to the spreader ends. That's my opinion, anyway. Good luck with the restepping. I've done it many times but still a bit stressful until it's all in place.

Chas

 

[vyv_cox]

Thanks both. The spreader ends have a screw down clamp however the wire is a loose fit in the clamp. I was thinking of wrapping the wire with amalgamating tape so the clamp can bite in it for securing?

Nothing can prevent water from running down 1 x 19 wires. Wrapping it with tape of any sort simply traps the water inside, ensuring that it is almost always wet. This is a sure recipe for crevice corrosion over time. Far better to leave all these types of fittings open so that the air can dry them as soon as the rain stops.

 

[rajjes]

Good point! What about a small piece of split hose round the shroud for the clamp to tighten on. Would it still risk crevice corrosion?

What is the recommended practice for seizing shrouds to spreader ends?

 

[alahol2]

My shrouds pass through a hole in the spreader ends which prevents them jumping off but are otherwise unconstrained. The spreaders are perpendicular to the mast which is the way many boats are designed despite the logic of having them canted up to bisect the angle of the shrouds. The boat is now 36 years old so the design obviously works.
If I were you I would not put anything around the shrouds to make them tight in the end caps.
It could be worth putting a pair of spreader boots on to reduce chafe on the genoa if it overlaps.

 

[Salty John]

Selden masts state:"The spreader ends must never, under any circumstances, be allowed to slide on the shrouds. When the mast has been stepped, it must be possible to stand on the spreaders without the ends sliding".

With multi-spreader rigs it's the intermediate spreader that locks onto the shroud, the cap shrouds are allowed some movement.

Some shroud bases are substantial fittings that hold the spreader securely at a specific angle, but even then the spreader tip mustn't be allowed to work against the shroud, as per Selden comment above. By the way, Selden specify a spreader angle of 6 degrees upwards, rather than specify that the angle with the shroud be bisected.

 

[TimBennet]

By the way, Selden specify a spreader angle of 6 degrees upwards, rather than specify that the angle with the shroud be bisected.

That's because they design their rigs with an angle of 12 degrees between the top of the shrouds and the mast. The 'rule' is to always bisect the angle.

If your spreaders don't bisect the angle, then a bending moment is being exerted on the spreaders and they are not solely in compression. This bending moment might be adequately resisted by the spreader base or outboard end fixture (for decades even), but the forces are constantly trying to force the spreader tip down.

 

[rajjes]

That's why I'm confused and the different opinions are not making it better

Most of the articles I found including the Selden guide are adamant in securing the spreader tips at an angle. However the boat has been for decades with perpendicular spreaders which are not seized to the shroud.

Should I take the 'if it worked so far leave as is' or attempt to improve the setup as recommended? If so, how does one secure the shroud without risking some sort of corrosion?

 

[alahol2]

Use it as designed. I'm sure you've got plenty of other things on your list to keep you occupied.

 

[Rigger Mortice]

If it's been OK before then leave it as it is.
In any event putting tape or a bit of hose over the wire will be unlikely to properly secure the spreader against the loads involved. It would simply pull through.

 

[vyv_cox]

My Selden masthead rig has a screw on each spreader tip that is driven into the wires. This holds everything securely in place. I used to have the silicone rubber spreader end covers but I didn't like what I was seeing beneath them, so I took them off. My sail has a couple of sacrificial patches instead, although my spreader tips are rounded and there has never been any damage.

 

[alahol2]

My Selden masthead rig has a screw on each spreader tip that is driven into the wires.

Eeek!

 

[vyv_cox]

Eeek!

It's only a flat ended screw. Been there a long time now, never a problem.

 

[theoldsalt]

That's why I'm confused and the different opinions are not making it better

Most of the articles I found including the Selden guide are adamant in securing the spreader tips at an angle. However the boat has been for decades with perpendicular spreaders which are not seized to the shroud.

Should I take the 'if it worked so far leave as is' or attempt to improve the setup as recommended? If so, how does one secure the shroud without risking some sort of corrosion?

I know what I would do and I am qualified to have an opinion but you should not take my word for that and although that opinion agrees with some already given I don't see it will sway your decision.

The problem with seeking advise on any forum is that you are bound to get much conflicting advise from (perhaps) well meaning but nevertheless unqualified fellows - with one or two notable exceptions.

Never assume that what anyone else, or previous owner, has done is correct; and please bear in mind that even some riggers get it wrong !

So if you are really concerned seek KNOWN professional advise.

P.S. I will add that Selden does seem a good place to start.

 

[vyv_cox]

Eeek!

Just checked the Selden Rig Tuning book and my memory has let me down (again!). The screw doesn't act directly on the wire, there is an aluminium pad between the two.

 

[Rigger Mortice]

http://www.moodyowners.net/moa_home.shtml

 

[William_H]

Just talking spreaders in general and not specific to any boat. Greatest safety is acheived by making and keeping the spreader end load in perfect column. So spreader bisects the angle of direction change of the shroud. ie typically some few degrees up. This would require that the wire be clamped to maintain that angle so perfect column.
Now if you look at the geometry if the spreader base is robust in holding spreader at rightangles to the mast (or 6 degreees up) any small change of compressive direction is not going to affect the spreader very much. ie not enough to cause it to colapse. Hence some boats have had spreaders at right angles to the mast for many years without concern.
Likewise many including mine have a wire which can move in the spreader tip without concern over many years. I think it very desirable to be able to adjust the tension of the cap shroud from the bottom and know that the wire is tensioned equally above and below the spreader tip without any influence of the spreader (up or down).
So it is a matter of design of the rig. On large boats with more critical rig design yes it is important to get the angle right and to clamp the wire. Do not distort or damage the wire at all as it is liable to fail at the stress point. Bigger rigs of course have discontinuous rigging so there is an attachment at the spreader tip so no question.
For smaller boats the spreaders and base are usually very strong, spreader quite short and can stand huge out of column loads so no concerns.

While on the subject of spreaders.If they are swept aft and are used to provide forward thrust on the middle of the mast they must have a very robust base and strength to withstand bending forces forward. So if a spreader is strong enough for this job in a fracttional rig it will (usually) be very strong to take end loads even out of column.
The term in column relates to loads being perfectly in line with the long post. The load direction in which great loads can be taken. Any off centre or off in line is called out of column and can induce bending or buckling in the pole post or column or its mounting.
Do make sure the wire is captured in the spreader tip if not clamped. I was sailing on a 24fter when the wire escaped from the spreader tip. On tacking the mast nearly came came down due to no shroud tension. Investigation found it was held in with string both sides. Shrouds inevitably go loose on lee ward side so don't rely on a deep slot for them to sit in.
good luck olewill