OK...I know that this is a subjective question and i am willing to take the abuse...
How much mast rake should I be running in 25 knot winds on a Nacra 5.5. My current answer is "MORE" since I buried the bows the last couple of times out.
I was able to hold for a few hours at 15-20 knots hull speed, but the bow was threatening the whole time. On the trap with extra weight and way back, the bow was safe.
I figure that I am one or two holes off of the right config.
At this point 14 inches off of the trap is mid rear inspection port. I think it should be closer to rudder.
Andrew....this is definitely in your ballpark. At some time I am coming to Florida to sail with you (preferrably on your M5.5).
Rich...Texas.
edited by: rpiper138, May 14, 2009 - 11:33 PM
Mast Rake
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Posted: May 15, 2009 - 12:33 AM
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Posted: May 15, 2009 - 09:15 AM
I think your settings are correct... at 25 knots you better be trapped out hanging off the stern... and if thats enough to keep you from pitching.... ye haw!
Your cat doesn't have deck lids (if i recall) so burying the bows is not a big deal.. i do it in big air, and i love it! i like the bow top just skimming the water. water puking everywhere! PARTY!!!
I have stuffed my bows up to the front beam. that pretty much stops my forward movement but i can recover from it.
the other methods to depower come into play here (down/outhauld, moving jib leads back to dump air... etc)
also... if your sails are blown out (stretched) this will work against you in big air as they will be fuller... (you want them flat in heavy air).
since the wind usually changes throughout the day.. there is no way to tune it for every condition... i would just make small single adjustments and see what works best for you.
edited by: andrewscott, May 15, 2009 - 09:18 AM -
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Posted: May 15, 2009 - 12:32 PM
Thanks. I may try one hole further aft to get the bows a little higher. I cartwheeled her last time out and although it happened in slow motion, there was mothing I could do to stop it. -
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Posted: May 16, 2009 - 12:31 PM
Perhaps raking is design dependent. I rake for ease of control which on my G Cat is all the way forward. Very little helm effort at all speeds. I have had my bows be shoved into the water but never submerge, perhaps due to the flange adding resistance. Lots of mad spray but very predictable. I like predictable.
Basically one has to get to know the traits and limitations of one's own boat.
I told a monohull sailor that I could influence how well my cat turned in a tack by where I placed my body weight. He thought it ridiculous. I thought him unexperienced despite his being a ship captain. -
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Posted: May 16, 2009 - 01:07 PM
I agree with predictable.
The bow submerged on me a few times and I have cartwheeled the boat twice now. I even had crew with me one day and sent the crew around the forestay.
I suspect that I have the righ 1 or 2 holes too far forward for the 20+ knot wind conditions. I think it is setup for 8 to 12 knots right now. -
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Posted: May 16, 2009 - 11:33 PM
The only time my bows threaten to submerge is on a broad reach, I have capsized 18 times in my sailing career, all on the same 5.7, but never a pitchpoll. Being able to remember the conditions leading up to a critical point of no return I adjust accordingly. This is where it is very important to have good blocks. It is those hammer blow gusts that really scare the bejesus out of you. As pointed out that you leave the dock with a certain set and twenty minutes later you are biting the deck with your butt in a sudden T storm.
That is why I rake for comfort at the helm. I have gotten 25 knots out of her, that is good enough for me. Lots better than rowing a canoe. -
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Posted: May 17, 2009 - 07:36 PM
Mine tend to go under on a broad/beam reach with high winds (20+) and decent sized waves. I've been over way more than 18 times, in fact I have probably made 18 times in 3 or 4 outings.
I don't have a lot of crew weight (me at 180 lbs) and I can keep the bows reasonably high when the wind is a little lighter and I am trapped at the back of the boat. As the wind builds, the bows start to bury.
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Posted: May 18, 2009 - 07:57 AM
Rich... you are doing great... fair weather never made a good sailor. Glad to see you made it back each time. Still... it is a pain to exert so much effort to get righted again. It can be exhausting. -
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Posted: May 18, 2009 - 11:10 AM
You didnt say that in your first post! you said you could "hold for a few hours at 15-20 knots".
if in fact you are pitchpoling... by all means depower it a little with rake when you rig it... -
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Posted: May 18, 2009 - 03:59 PM
Yeah Andrew, I can hold it in 15-20, but once I hit 20+ the bows get heavy. -
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Posted: May 18, 2009 - 04:04 PM
Thanks Deepsees,
I tend to spend so much time in the water because of the high winds here in Dallas and the fact that I single hand a lot. It isn't that new to me since I sailed much less stable boats in my younger years. Some of the pitchpoles on the I-14 were much more spectacular than the cartwheeled Nacra, but the I-14 pretty much stops when it throws you 50 feet in front of the boat. The Nacra starts to run away from you. -
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Posted: May 19, 2009 - 01:22 PM
I don't know the specs on the N5.5, but I would think you also need to counteract the mast rake with rudder rake to maintain a relatively neutral helm. On my boat I had some serious weather helm and then one day while sailing in big wind with lots of downhaul and mainsheet, the helm felt near totally neutral. Two fingers on the stick in 25+ winds. WTF?
Of I course when I put the boat on the trailer and noticed how screwed up my mast rake was - it all came into focus. Duh!
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Posted: May 19, 2009 - 03:01 PM
That is definitely true DOug. I have the rudders raked under the boat so that the center of force is just slightly aft of the rudder pivot point.
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