General Info: Boom to Main Sheet Block Mounting

[AZ_Zoner]

Is there a reason that Lagoon connects the main sheet blocks to the boom with lines vs using sliders on the bottom of the boom?
I've been thinking of installing 2 sliders at the back but just saw a brand new 42 Lagoon and it is using the lines wrapped around the boom.


Craig

[UNCIVILIZED]

I can't speak as to Lagoon's reasoning, but Spectra's been good enough for just about every major racing boat built in the last 2 decades. It could be due to a strop which wraps around the boom spreads the load out a bit more, which is kinder on the extrusion. Not to mention that you see them wearing prior to their breaking, & thus can replace them prior to anything catestrophic happening.

[AZ_Zoner]

The sliders I'm looking at are 6" long so will most likely get more load distribution over the two mounting locations than what are with the line wraps.

Is it just not wanting to give up old school methods for a newer and possibly better way of mounting the blocks? Why would the boom have the T groove in them if they weren't to be used?

Also Lagoon wraps the reefing lines around the boom instead of using the T groove on the top of the boom for sliders. I've seen a few other manufactures, both mono and cat, using sliders in both cases and when the sliders are used it really cleans up the appearance. But performance comes first and I'll only make the changes if that is not compromised.

Thanks for your input and would like to here more.

Craig

[Jim Cate]

We have used webbing strops for all line attachments to the boom for years. Very strong, better load distribution, very inexpensive, adjustable position if required. We use spectra based webbing for the clew outhaul attachment, the rest are simple 'seat belt' webbing. Three wraps around the boom, can be sewn in place or prestitched if it can be slid over theboom without too much trouble. We keep one that is secured by velcro (sounds crazy, but the sailmaker said his big raceboats use such things) for emergency replacement.

OOps... I lied! We just tie the three reefing lines around the boom... no strops involved!

Jim

[UNCIVILIZED]

There's no one way that's correct, or best, for attaching things to a boom. And in fact, the number of ways you can do it are limited only by your creativity.
Spectra, & webbing, are cheap, universal, & easy to use/DIY. Where fittings can be specialized, & generally cost a good bit more (often hugely more), without offering much advantage. They're also heavier, along with the earlier mentioned bit about their not giving much, if any, warning prior to breaking. Unlike cordage or webbing.

It sounds as if you're curious to learn more about rigging, but sadly, other than Brion Toss's works, I can't tell you were to look. As I've never come across a formal tome on rigging. And actually wish that there was more in print on the subject. So if you run across a good source of info, please share it. Otherwise, you/we are stuck learning rigging in bits & pieces, over time. Mostly by sharing info with other sailors when assembling or fixing something on a boat/rig.
Oh, there's some info in the Dashew's books, & of course ones such as Skenes.

[transmitterdan]

The groove in most booms is not designed to handle sheet loads. The extrusion probably just has the groove matching the one for the sail track and it would create a non-standard part to not have it. Putting a few turns of line or webbing around the boom is the safest method of attaching the sheet block.

[meirriba]

Originally Posted by AZ_Zoner

Is there a reason that Lagoon connects the main sheet blocks to the boom with lines vs using sliders on the bottom of the boom?
I've been thinking of installing 2 sliders at the back but just saw a brand new 42 Lagoon and it is using the lines wrapped around the boom.


Craig

As a rule, I would prefer line/strop solution to a slider. The reasons are already pointed out.
Just consider the current trend of soft shackles replacing metal shackles.
On our Nacra 6.0 racing beach cat we have replaced almost all s/s connections with soft solutions. As almost any on water failure puts the crew in the water we like to be able to monitor wear & tear and replace anything before it fails.

[Stumble]

Originally Posted by UNCIVILIZED

There's no one way that's correct, or best, for attaching things to a boom. And in fact, the number of ways you can do it are limited only by your creativity.
Spectra, & webbing, are cheap, universal, & easy to use/DIY. Where fittings can be specialized, & generally cost a good bit more (often hugely more), without offering much advantage. They're also heavier, along with the earlier mentioned bit about their not giving much, if any, warning prior to breaking. Unlike cordage or webbing.

It sounds as if you're curious to learn more about rigging, but sadly, other than Brion Toss's works, I can't tell you were to look. As I've never come across a formal tome on rigging. And actually wish that there was more in print on the subject. So if you run across a good source of info, please share it. Otherwise, you/we are stuck learning rigging in bits & pieces, over time. Mostly by sharing info with other sailors when assembling or fixing something on a boat/rig.
Oh, there's some info in the Dashew's books, & of course ones such as Skenes.

I got an email from Toss yesterday mentioning that his new, updated, book is almost read your for the printers. Aparently it is going to include some more technical and esoteric rigging stuff. So it looks like I will be buying at least one print book next year.


On the wider note. One of the reasons for moving to webbing on booms is that with the advantage of carbon booms there is a serious desire NOT to drill or tap into the extrusion. Carbon is far less tolerant of holes than metal and because it is galvanically more noble than stainless it makes the fasteners the anode (on an aluminium boom the entire boom is the anode spreading the damage out over its entire surface).

To eliminate these issues stramps and webbing were developed, and since they work fine, are cheap, and actually more adjustable than riveted hardware have started takin get over even with aluminium extrusions. It eliminates weak points, spreads the load out, and I still cheap to make, the better question is why wouldn't you use them.

One more data point... on the Turbo 70 I sailed on, our clew was attached with 3 wraps of Velcro strapping around the boom. It never came close to releasing.

[UNCIVILIZED]

The thing with Velcro is that like many other products, there are many grades (strengths) of it available. In addition to coatings to assist in making it resistant to different forms of degradation. So it'd probably be wise not to use cheap s**t Velcro for high load applications.

[SVNeko]

I have always wondered how you keep the strop in place on the boom when the line pulls at an angle other than perpendicular. I would expect it to slide bit by bit when the tension is off. Do they build in little high spots to stop the sliding?

[transmitterdan]

Originally Posted by SVNeko

I have always wondered how you keep the strop in place on the boom when the line pulls at an angle other than perpendicular. I would expect it to slide bit by bit when the tension is off. Do they build in little high spots to stop the sliding?

On our boat there are some small eye straps inserted into the lower side track. These would make a handy way to lash the loop if the sail is loose footed. If you have a slides on the sail in a boom track then that will keep the strop from going walkabout.

[Stumble]

Originally Posted by SVNeko

I have always wondered how you keep the strop in place on the boom when the line pulls at an angle other than perpendicular. I would expect it to slide bit by bit when the tension is off. Do they build in little high spots to stop the sliding?

It isn't really an issue. The sail wants to pull the strop forward, the outhaul acts as a lock to keep it in place.

The only time you ever really need a stop is when you use strops for a midboom mainsheet control or similar. In which case there are a couple of options, but the most elegant is to build in a little carbon knee or shelf to hold it in place as you suggest. You can also use a rivet or bolt thru the strap. It's somewhat like a lock stitch in dyneema splices, it's really there's justto keep it from sliding around while untensioned. Once the line I see loaded up the wrap grips the surface of the boom and locks it into place.

[SVNeko]

Originally Posted by Stumble

It isn't really an issue. The sail wants to pull the strop forward, the outhaul acts as a lock to keep it in place.



The only time you ever really need a stop is when you use strops for a midboom mainsheet control or similar. In which case there are a couple of options, but the most elegant is to build in a little carbon knee or shelf to hold it in place as you suggest. You can also use a rivet or bolt thru the strap. It's somewhat like a lock stitch in dyneema splices, it's really there's justto keep it from sliding around while untensioned. Once the line I see loaded up the wrap grips the surface of the boom and locks it into place.

That's sort of what I expected. I have an Alu boom with main sheet blocks in a slot on the bottom of it. So if I wanted to do this I'd put in some kind of mechanical stop to keep the dyneema strops in place.

[PaulinOz]

"I have always wondered how you keep the strop in place on the boom when the line pulls at an angle other than perpendicular. I would expect it to slide bit by bit when the tension is off. Do they build in little high spots to stop the sliding?"


My L450 setup from factory. Strops held in place by 3 Pad Eyes mounted on top of boom.

[SVNeko]

Thanks, Paul. Helpful. All that, and they left the metal shackles on the blocks.