I know I had a thread on this a while back, but I would like to revisit the Mac’s tendency to broach. I believe I have tamed the Mac beast in virtually all conditions except one. The one point of sail I always have problems with when winds are heavy and seas are big is a broad reach. The boat is so light, especially around the stern, that it just broaches in quartering seas & big winds. It seems like there is virtually nothing I can do about it. The quartering wave, combined with the lever effect of the wind on the mainsail just whips the boat 90 degrees towards windward, ending up on a close reach with sails flogging and a broken rudder (different post.) This has been a common problem for me in heavy conditions. Everything I read on broaching entails the bow digging in as the sudden decrease in forward progress combined with waves astern cause a rudder stall and the boat whips around. I am not quite sure if the bow is digging in. Sure doesn’t feel like it. Even with reefed main, I can’t stop this from happening. I have a few ideas which I have yet to implement which include:
Furling in the jib.
Pulling up the DB all the way or perhaps leaving a foot in the water (may the boat trips over its keel.)
Tilting the engine down. I just hate to do this but I was told it would help.
Would appreciate some feedback and additional ideas.
Leon.
Broaching
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beene
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Hi Leon
Why so against putting the motor down?
I know in the pure sailing world that is taboo, but our boats aren't pure sailing boats. I have read that having the motor down slows you up so little you would not even notice a speed change when sailing.
Now that the 75 is on, I know I will be sailing with the motor down, all the way down, unless of course I get that handy BWY quick disconnect thing that you have. Even then, the motor will be touching the water.
G
Why so against putting the motor down?
I know in the pure sailing world that is taboo, but our boats aren't pure sailing boats. I have read that having the motor down slows you up so little you would not even notice a speed change when sailing.
Now that the 75 is on, I know I will be sailing with the motor down, all the way down, unless of course I get that handy BWY quick disconnect thing that you have. Even then, the motor will be touching the water.
G
Looking at the boat from above, here's some guessing for what it may be worth.
Your mention of the lever effect sounds right . Broad reaching with no headsail and main CE past the rail and far from the boat centerline as well as being somewhat farther fwd, DB is down so CLR is as far fwd as it can be, and so a puff pivots the boat horizontally about the fully down DB (despite rudders) into a close reach or upwind orientation. Weathercock effect.
With both rudders down, pulling DB partly or fully up would move CLR aft, maybe even aft of the main's CE. If so, less weathercock effect.
With main down and headsail up, sailplanCE is well fwd of CLR and so weathercock effect and broach tendency should be absent, per my best guess.
Good luck.
Ron
Your mention of the lever effect sounds right . Broad reaching with no headsail and main CE past the rail and far from the boat centerline as well as being somewhat farther fwd, DB is down so CLR is as far fwd as it can be, and so a puff pivots the boat horizontally about the fully down DB (despite rudders) into a close reach or upwind orientation. Weathercock effect.
With both rudders down, pulling DB partly or fully up would move CLR aft, maybe even aft of the main's CE. If so, less weathercock effect.
With main down and headsail up, sailplanCE is well fwd of CLR and so weathercock effect and broach tendency should be absent, per my best guess.
Good luck.
Ron
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delevi
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ronacarme,
What you're saying makes a lot of sense. The reason I'm thinking to go with main only vs jib only is the potential for the bow to dig in. Abscent the jib, I would think the bow would ride higher. Of course, the direction of air on the jib vs main would make more sense i.e. no big lever arm to push to spin you to windward, rather the opposite with the jib. Unfortunately, it's much harder to drop the main than to furl the jib in rough conditions.
Geoff,
I notice an average of .5-.75 mph difference with the engine tilted up. Mine touches the water too, but ever so slightly and the prop is out of the water. If you ever try the BWY engine linkage, you'll be hard pressed to sail with the engine connected again. Trust me on that one. Of course, if it means not broaching, that babie is tilting down. I'll need to try that.
I also never tried raising the DB, but reading about broaching and the boat tripping over its keel, as well as James' & ronacarme's comments, I think this is a worth-while experiment.
When I wrote tilted down, I meant all the way down. Up, all the way up. I never tried anything in between. Don't really see a reason why.
What you're saying makes a lot of sense. The reason I'm thinking to go with main only vs jib only is the potential for the bow to dig in. Abscent the jib, I would think the bow would ride higher. Of course, the direction of air on the jib vs main would make more sense i.e. no big lever arm to push to spin you to windward, rather the opposite with the jib. Unfortunately, it's much harder to drop the main than to furl the jib in rough conditions.
Geoff,
I notice an average of .5-.75 mph difference with the engine tilted up. Mine touches the water too, but ever so slightly and the prop is out of the water. If you ever try the BWY engine linkage, you'll be hard pressed to sail with the engine connected again. Trust me on that one. Of course, if it means not broaching, that babie is tilting down. I'll need to try that.
I also never tried raising the DB, but reading about broaching and the boat tripping over its keel, as well as James' & ronacarme's comments, I think this is a worth-while experiment.
When I wrote tilted down, I meant all the way down. Up, all the way up. I never tried anything in between. Don't really see a reason why.
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baldbaby2000
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Leon,
I'd try number 2: bring the board up. I've done this and it's helped. I've heard of people bringing it all the way up and crabbing along. You'll loose a big part of the the weighted keel advantage however.
You might be OK with sailing on just the headsail since you've added running backstays but I wouldn't suggest others do this with the stock boat in the winds you sail in.
Daniel
I'd try number 2: bring the board up. I've done this and it's helped. I've heard of people bringing it all the way up and crabbing along. You'll loose a big part of the the weighted keel advantage however.
You might be OK with sailing on just the headsail since you've added running backstays but I wouldn't suggest others do this with the stock boat in the winds you sail in.
Daniel
and 
boats on this topic - the Broaching
Pull the board up!. The Mac likes being a big fat surf board. Who cares if you crab a bit when you're doing 7 - 9 knots in plenty of breeze. Agree that the rudders don't like it - on to my 3rd repair at the moment.
Rudders
The stock rudders tend to crack and break above the bolt hole. The top of the rudder is filled with resin to resist compression but this doesn't resist lateral forces.
The gudgeons (the stainless brackets the rudders fit in to ) are too small and will splay apart over time decreasing the support for the rudders. Something I might get one of my metal fabrication mates to have a look at.
Keep in mind that we here on Port Phillip sail in relatively heavy conditions, similar I imagine to San Francisco. Also keep in mind that the steering and rudders are a weak point in all yachts - the forces exerted are huge. Have a look at the retirements from ocean races and steering failure will be a common cause. Consequently backup steering systems are compulsory on all ocean racers. One boat I crew on at times retired from a race a few months ago when the whole rudder and shaft dropped out of the bottom of the boat, which meant steering by drogue at 3 knots for over 100 miles!
The gudgeons (the stainless brackets the rudders fit in to ) are too small and will splay apart over time decreasing the support for the rudders. Something I might get one of my metal fabrication mates to have a look at.
Keep in mind that we here on Port Phillip sail in relatively heavy conditions, similar I imagine to San Francisco. Also keep in mind that the steering and rudders are a weak point in all yachts - the forces exerted are huge. Have a look at the retirements from ocean races and steering failure will be a common cause. Consequently backup steering systems are compulsory on all ocean racers. One boat I crew on at times retired from a race a few months ago when the whole rudder and shaft dropped out of the bottom of the boat, which meant steering by drogue at 3 knots for over 100 miles!
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Frank C
Good feedback, AJ, but it's rare to see.
Fact is, your's is the first report I've seen of a cracked rudder or bracket problem. That's probably because 90% of these boats never see more than 20 knots of wind. Mine have survived up to about 24 knots on SF Bay, but I head home when the speeds get much over a "20-average."
If you have a picture of an upgrade to the stainless bracket, I'd like to see it. In fact, I'd like to see it posted into the MacMods pages. I can't even visualize a way to strength those brackets without fully replacing them with a heavier thickness of steel.
Fact is, your's is the first report I've seen of a cracked rudder or bracket problem. That's probably because 90% of these boats never see more than 20 knots of wind. Mine have survived up to about 24 knots on SF Bay, but I head home when the speeds get much over a "20-average."
If you have a picture of an upgrade to the stainless bracket, I'd like to see it. In fact, I'd like to see it posted into the MacMods pages. I can't even visualize a way to strength those brackets without fully replacing them with a heavier thickness of steel.
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Lease
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Port Phillip Bay is a real test for the Mac. I've been out a few times, but it is just plain uninteresting for the family, and I've had a few cases of people actually getting seasick out there. It's very large which means there is a lot of fetch and consequently lots of wave action.
This past season was extraordinary with big breezes almost all the time:
Here is today's breeze so far (and it's only 11AM):
Edit: That's odd, the pic works fine on the preview, but not on submit - Well it's blowing 25, with gusts to 30 at the moment.
Here was a nice Sunday for a sail in February:
This past season was extraordinary with big breezes almost all the time:
Here is today's breeze so far (and it's only 11AM):
Edit: That's odd, the pic works fine on the preview, but not on submit - Well it's blowing 25, with gusts to 30 at the moment.
Here was a nice Sunday for a sail in February: