How Much Load on Halyards ?

[rhr1956]

I am about to install some blocks for routing halyards to the cockpit. (Pearson 26) I am torn between un stepping the mast and mounting the blocks to the mast with bolts and nuts...or...leave the mast alone and thru bolting the blocks to the cabin top. I'm guessing based on how hard I pull down to raise sails, there is maybe 75-100 lbs load on the halyards. Using 1/4" starboard for backing plates, how many square inches of the stuff should I cut to make a proper installation? I've already cut some pieces about 1" X 3" but I'm wondering if I should make them bigger. Thanks for any advice.

[osirissail]

Cabin tops are not really stressed for vertical loads. Unless your mast is deck stepped and not keel stepped is not wise to attach turning blocks to the cabin top. Instead attached them to the mast either directly or by the use of a collar around the mast at deck level.

Hayards are tensioned to "stretch" the sail upwards which will in turn impart an upward load on any block that is attached to the cabin top. As the boat moves through the waves/oceans the cabin top will be flexing up and down promoting the chance of cracks and failures around the mounting point of the halyard blocks.

[Valkyrie654]

The loads on halyards can be very high. I would go larger on your backing plates but I would not use starboard unless it's very thick. The stuff will bend. I like to use G-10 Fiberglas plate. For your size boat go with at least 1/4" thick. You can cut it with hand tools and is very stiff. Keep them as close to the base of the mast as you can. Or as others have said, keep them on the mast itself or on a plate under the mast. Your Pearson is deck stepped, but on many boats with keel stepped masts you will see either a tie rod going to the keel, or straps through bolted to the mast to keep the deck from being pushed up from the compressive loads from the shrouds.

Keep the number of turns to a minimum. Every turn adds friction, which in turn makes it harder to get the job done when compared to just leaving everything the mast.

[RicknSue]

'Keep the number of turns to a minimum. Every turn adds friction, which in turn makes it harder to get the job done when compared to just leaving everything the mast.'

Agreed completely- My main halyard came off the sheave this year(was riding on the bolt that goes through it and between the sheave and mast), and I could still raise my sail from the mast with nothing other than me(no winches,et al-still a little effort) , my buddy's one foot bigger boat, with the main ran back through a block, deck organizer, and clutch to the cockpit- forget it, you aren't doing it without a winch (and he's bigger than me by about 30 lbs)

[Weyalan]

Personally, I wouldn't attach halyard blocks to the base of the mast. I'd also not use the cabin top as such, unless it was adjacent to a bulkhead or ring frame to take the load. Often you can mount halyard turning blocks on the plate/frame whether the mast is either stepped onto the cabin top or goes through the cabin top - this location should be more suited to the loads associated with the halyard.

If you want to get an idea on the loads your halyard will see, there is a reasonable formula to calulate it in the first chapter of the Hrken Catalog, where you can work out the loads based on sail area dn wind strength...

[Bash]

1/4" starboard for backing plates?

I can't imagine why you'd want to do that. Even plywood would be better.

[osirissail]

Originally Posted by Valkyrie654

. . . Your Pearson is deck stepped, . . .

Look carefully at the base of your mast up on the cabin top and then look down in the cabin - it will be extremely obvious if the mast continues down "through" the cabin top into the cabin and down to the keel.

Assuming you are "deck stepped" - then around and under the base of the mast will be a large "plate/fitting" that holds the mast. It will normally have "ears" or sections of it that protrude out and away from the base of the mast. Normally there are also holes in this part which are used for attaching various blocks such as turning blocks for the halyards.

If they do not exist, you can have a stainless plate made that will slip underneath the bottom of the mast and will have holes in it for attaching blocks.

Alternatively, you can have a strap collar made that will clamp around the base of the mast above the cabin top and has attachment points for blocks for halyards, etc. These "collar(s)" work just like hose clamps and tighten around the mast tube. They also avoid having to drill any holes into the mast tube. All the forces from the halyard are now strictly on the mast tube and not transferred to the cabin top.