Rrd boom head diameter

[Socalsailor]

Trying to replace with a streamlined rdm head. Model is rrd vr150. I was assuming the rrd would take the smallest diameter boom head.

[isobars]

Not necessarily.
You need to measure the outside diameter of the RRD boom front end and see whether it's compatible with the Streamlined head, based on website specs or actual measurement.

I have the previous model of Streamlined RDM head cheap if you don't want to pay the extra $100 for the latest mast-fit/"inhaul" adjustment design. My older models will slip one or two mm over a couple of days' use, and are marked so I can tell at a glance when it's time (and how much) to snug 'em up. Isthmus tells me Streamlined heads must be very tight on the mast else risk failure.

[Arrgh]

This is a good time to pick up a vernier caliper if you don't already have one. It is one of those tools that you will wonder how you ever lived without. A $10 one is all most of us will ever need.

[kevinkan]

The standard thickness bushings for the Streamlined head will fit boom tubes ~36mm (USA HPL booms, Streamlined booms). Many of the Aeron-made carbon booms have tube diameters a little smaller than that. The NP X7 and earlier X9 booms had something in the 34mm range I believe. There are a few different RRD booms with different heads and front tube thicknesses... they had booms made by at least two different companies. If you want, send me an email w/ some pictures of your boom, and I will try to help you figure it out.

I sell the Maui Sails and Streamlined Dyneema head. The Maui Sails comes w/ two different thickness shims to adapt to different tube diameters, and they can be modified/stacked to fit NP booms (or other booms w/ small tube diameters). The Streamlined can be ordered w/ different thickness urethane bushings to fit different booms.

[Socalsailor]

Isobars, you said it has to be tight but how tight? I ask because I nearly cracked a carbon mast once using a shitty head-had to overtighten to prevent slipping. Any reviews on the rrd head?

[isobars]

Ahhhhh .. that's the $800 question, isn't it? I don't know the answer. But the Isthmus guys said, "very tight", and added:
• No visible gap in the bushing.
• Those small Streamlined levers don't have the leverage to crush a mast.
• Most Streamlined fractures are from mast levers/straps that are too loose.

With Streamlined heads, I have to loosen the outhaul if I want to loosen the head clamps to adjust boom height. Since I may do that offshore, I switched to Maui Sails heads on my Streamlined booms ... freeing up my Streamlined heads for holding down papers on my desk. Good conversation starters (even at WSing swap meets, where most WSers don't even know what they are). I now use only one Streamlined head, on my 3.2 boom which gets used maybe 3-4 times a year. Even then, I may still convert to a Maui Sails head as insurance against hassles I don't need in 3.2 conditions.

I once heard one single, subtle crack as I tightened a long-levered boom head on a new SDM without using a shim. First jibe, the crushed mast snapped, leading to the loss of a new sail AND the mast plus a one-kilometer swim. I sold all my SDMs the next weekend and now use only RDMs (with thick walls) and only with shims/spacers or heads that do not slip even when barely snug. "Performance", to me, includes reliability, and I don't race or use huge sails.

[kevinkan]

In my experience, the older Streamlined "Strap-On" boom heads w/ the wide-black straps (instead of rope) had to be adjusted very tight on the mast. There was very little tolerance between too loose, too tight, or just right. The lever tension had to be adjusted accurately to prevent slipping, but once adjusted, it was a nice, rock solid connection. Also, the way the straps slid w/ some friction on the urethane tongues, you had to release the outhaul tension completely if you wanted to adjust the boom height on the water. Those wide, black straps have almost no stretch, so if you did overtighten and forced things, I could see how you could break a mast.

With the new Streamlined Dyneema boom head, there is a much larger sweet spot for correct tension, and one setting for me works with multiple masts on multiple sails. If an adjustment is needed, it is easy and can be done on the water. Also, the Dyeneema rope slides easily through the Delrin rope guides, so I can adjust boom height on the water without loosening my outhaul. With this head, I think the rope has a little more stretch, and it would be much harder to crush a mast by over-tightening.

http://www.sunsetsailboards.com/shop?page=shop.product_details&flypage=flypage_images.tpl&product_id=1513&category_id=24

[gerritt]

Adjusting a boom head on the water, especially without loosening the outhaul, is a recipe for disaster. I've seen more than one broken mast as a result. Even on shore, adjusting the head without first loosening the outhaul can snap a mast -- even the RDMs.

Take the time to get familiar with your settings and then stick with them. For the occasional sailor, or the guy on rental gear, if its just not right once under way, come in and spend five minutes on shore rather than risking a long long swim (or worse).

In the environments we put ourselves in, a small problem can turn into a big one very quickly.

[isobars]

Please explain how unclamping and reclamping a boom head with the outhaul hooked up (my OH tension runs nearly neutral) can -- let alone is likely to -- threaten the mast; you might save me (or someone who listened to me) a swim.

The only perceptible force in this process is the action of the water on the floating sail, which is minimal if not in surf. On land, my sail barely knows whether my OH is hooked up. In fact, I often rig and launch with an inch of slack in my OH if I suspect I'll need extra power to cross the wind shadow, then snug it up if I want less power once past the shadow. OH adjustment is effortless and takes less than 5 seconds offshore once in the water.

I change my boom height offshore primarily if I see a LONG slog coming (e.g., the wind backs way off when I'm kilometers or even miles away), in which I'd want to hook in while slogging. Or I may have the height off by an inch, worth fixing sometimes but not worth swimming across a wind shadow two more times. After all, changing boom height offshore is as effortless and quick as an OH adjustment.

Of course, YMMV with great big sails or race sails.

[beaglebuddy]

Socalsailor will be the first person to ever purposely install a Streamlined boom head on another brand boom.