1985 Cal 33-2 mast rake

[rcvesselstyn]

Reposted for Dolphin Cal33-2

Noticed your post related to mast rake, we're looking for recommendations on mast rake and rig tuning for our Cal33-2 HUNT.

We need to tune the boat for club racing, at present we haven't done much tuning, and need some direction. At present we know we have no rake in the mast, and shrouds need better tensioning.

1985 Cal33-2 #17
Sarnia Yacht Club
Lake Huron

[rcvesselstyn]

First off you should probably swing by West Marine or go online and get a rig tension meter. We had never used them in the past, we always did it by feel, but when I had my rigging replaced this summer I was impressed at how quickly the rigger initially tuned my rig using the meter. The method we have used for ages follows: 1. initial tuning lay on your back looking straight up the mast and preliminarily tighten each shroud until the mast is arrow straight. ( no mast rake ). 2. Take the boat out and on a beam reach, lay on the cabin top and check out the mast. The goal is to have the mast straight. Make a note of any lateral mast bend or twist. Go over to the other tack and adjust the lee shrouds according to your notes. Check for mast straightness on this tack and take notes. Just keep tacking back and forth adjusting The turnbuckles until you get it right. Zero mast rake. If you've already shelled out some bucks for a rig tension meter, when you get back to the slip you can equally adjust so you have the same tension on matching shrouds.
A caveat with all of this is make sure your turnbuckles turn freely. If you feel that any of them are galling or binding in any way when you do your initial tensioning replace them. Tuning is the most likely time when you're going to snap a turnbuckle. Another caveat is everyone seems to want to tighten their rig too much. The lee shrouds can be loose or at least soft when underway. Attempting to have your lee shrouds tight when underway is a good way to drive the mast through the deck, and it has no purpose.
Now about mast rake. When a naval architect makes his calculations he bases them on the mast being straight, not raked. This adjustment would be the very last you would want to change, and even then only after you've tried everything else. It would be in response to a constant extreme weather helm or lee helm that was not mitigated by different sails, different adjustments of those sails, and different weather conditions. The goal is to have a slightly weather helm but the best way to get that is by adjusting your sails.
Finally a note about mast bend. It looks like you have a roller furling headsail. This would mean that you have a fixed length headstay. If you're going to be racing it would be advantageous to be able to tighten and loosen the headstay to get a sharper leading edge and to flatten your headsail. If you do this with a backstay tensioner you also get advantages with the main sail shape if the main is cut for it. It looks like you have a single backstay. There are products on the market that will allow you to tighten the backstay while underway. Being able to control the headstay tension makes a huge difference when pointing. Many people forget that it has advantages off the wind or in light winds also, allowing you to have a fuller headsail. Without having an adjustable backstay you have to pick some sort of median headstay tension.
Lastly, just a disclaimer, this is just old advice from an old sailor. Good luck!

[Dolphin Cal33-2]

Thanks for the tuning details, greatly appreciated
We do have a hydraulic backstay and regularly use it to get better pointing and power
boat is on the hard for the winter, look forward to spring tuning once the mast goes up
Love your stories of sailing out to Catalina, we've been out to the island once on the ferry from Dana Point, we like to visit San Clemente and do some surfing in September
Cheers

[allen]

I don't know how similar your boat would be to a Cal-36 so you may or may not find this useful https://L-36.com/lapworth_letter.php. It is Bill Lapworth's take on rig tuning.

There seem to be two schools of thought on how tight to make the rigging. None say the leeward rigging should be tight under sail but one school has the rigging tighter than the other. One theory is that when underway in a stiff breeze the leeward rigging should be just snug so it doesn't bang around which can weaken it. The other theory is that have the rigging just snug at the dock and adjust the relative tightness so the mast is straight under sail or has a slight fall off. A mast is a long skinny column and you want the shape to be in the first mode and not an s-shape which is not close to as strong. The lower rigging prevents this because it is not in the center of the mast. Anyway, either theory can keep the mast in the first mode and that is important. The theory I subscribe to is what is in Lapworth's letter and basically says that if the rigging is tight enough to keep the leeward rigging tight, you will have too much stress on the boat at the dock. It will sail just fine either way. Maybe if you have an America's cup boat you care about the extra 1/4 degree of mast straightness but most of us would never notice. My leeward rigging flops about 5 inches peak to peak under sail. I out pointed almost everyone in our beer can fleet when I used to race.

The other topic not mentioned is pre-bend. If a boat does not have both forward and aft lowers, it needs pre-bend to keep the mast stable, so the middle doesn't flop around fore and aft. Some boats with forward and aft rigging get modified so there is only a single lower and in that case you need pre-bend. Otherwise, the pre-bend just has to match the way the sail was made and typically that is the other way around, the sail is made to match the boat. I had a set of sails redone because the designer assumed some prebend on my wood mast. If the sail and mast don't match, that is bad. Some boats adjust the pre-bend to tweak the last bit of performance out of the sails they have.

Finally, boats are faster when the forestay is tight. Mine was not that tight because I have an old wood boat. But this old rule of thumb might be insightful if not useful. Just tighten the forestay until the mast breaks, then back off a little.

[Dolphin Cal33-2]

Allen,

We appreciate Lapworth tuning directive & theory and recommendations
We're on the hard for the winter (Lake Huron), but looking forward to tuning in the spring !