MacGregorSailors.com

Yeah if those are 10 foot swells then you have a 50 foot boat!

I have felt similar issues in my X with big following seas. Put all your boards up with full ballast and try to ride on the back of the wave in front of you and match it's speed. This may mean giving more throttle to match the speed of the waves or slowing down so that you don't over run them.

http://www.docksidereports.com/rough_wa ... ship_1.htm

-Randy

It sounds exactly like powering a Mac in following seas. We get south winds almost all summer in very narrow,deep, long channels. I don't even bother powering anymore. If I can't do 10 knots comfortably; up go the sails. You make better time. You'd be kidding yourself if you think that the three seconds at 12kts you're doing down the backs of the waves is making up for the 30 seconds at 2kts you're doing up the next wave, not to mention working the sh#t out of your engine, swamping it and burning extra fuel. it is hard on the captain and the crew. If you put up your sail(s) you can fall asleep with one finger on the wheel (the admiral did this summer beside me in (actual) six foot following) No fighting the boat, just the whoooosh of every fifth wave or so as it settles around you.

OK help me here.. I am not seeing swells / wave heights that are 4 feet above the deck??????Ive been is big 6'es maybe more here and there and the waves were above the deck.. Very Noticeably Above the Height of my deck..
Why do I not see any splash? Or if its a following sea? The lift and drop as a 10 foot high wave picks you up , the deposits you In the trough and then rushes past you?? Am I Missing something here??? Looks more ( to me) like 3 to maaaaaaybe ....4's

I think some of you guys are being too hard on the Scots. I certainly have always found that when one looks at photos one has deliberately taken of big waves from the Mac it looks like we were on a mill pond. I write it off now as something to do with horizons and perspective ... and I don't even bother trying to record them on film anymore.

But as usual the bantering discussion has been very educational.
Kittiwake

You are over propped--you should be on a 13.75x13. The prop is part of the reason this happened to you, but it's not the major player.

So there's a middle ground between displacement speed of 6 knots and planing speed of 13 knots when the boat is "plowing" and is __exceptionally__ affected by wave action. In this range it is semi-planing--above displacement but not yet planing. It is moved around by waves just as you described. Pure planing hulls are not very affected because they are much flatter, and pure displacement hulls can't even get to these speeds. The Mac's semi-displacement hull is a compromise and wave conditions like these are an exacerbating condition.

Do not spend time in this middle ground. It's not pleasant in the best conditions and its terribly inefficient use of fuel. Think of the Mac as having two "modes": Displacement (below 7 knots) and planing (above 12 knots). The speeds between should be straight-line transition only--getting to a plane and getting off of it.

In any condition below planing where the boat feels "squirly" as you've described, the right action is to reduce speed to 6 knots (or the closest speed at which you can maintain speed in a trough between waves) and drop the boards. Resistance on the daggerboard will move the load aft, create a correct center of rotation for the boat, and the rudders will put real bite into the steering.

If you are motoring and sea conditions prevent planing, take the boat down below 6 knots. Think of it as switching modes.

Matt

Concerning the 14x11 prop - some people have stated that there is a problem with the selected propeller. I really do not agree. Assuming the stock prop is 13.75x13, this prop is only 1/4 inch more in diameter (negligible) and 2 UNDER pitch. I have made the same change because the ETEC 60 on an empty boat (mine) is fine but loaded up the motor tends to run under the recommended RPM range at WOT. This is clearly stated in the ETEC service manual as potentially damaging to the power head. I made this change after several discussions with Evinrude. I have yet to try the new prop.

I really think the better line of thinking concerns the amount of plane, the wave height and frequency, and the direction the boat was traveling. In a certain sea state, you just need to go where the boat wants to.

RobertB wrote:Concerning the 14x11 prop - some people have stated that there is a problem with the selected propeller. I really do not agree. Assuming the stock prop is 13.75x13, this prop is only 1/4 inch more in diameter (negligible) and 2 UNDER pitch.

Not to be argumentative, but prop pitch has a lot to do with the max speed the boat is designed for with a given hp engine. A displacement work barge won't go very fast, but may push a lot of water, and need a shallow pitch prop for a given engine at WOT. The same engine on a little speedster with a planing hull may push it to 30 or 40 mph or more, and need a deep pitch prop to avoid overspeeding the engine at WOT. The prop for a given engine has to match the application. I didn't think there even was such a thing as a standard prop, at least once you get bigger than dinghy motors. I've always heard that the acid test for prop selection, for inboards (even sailboat diesels) and outboards was that the engine would stay in its rated power band at WOT, regardless of the boat it's mounted on.

Not that it has anything to do with the OP's issues of near-broaching with a following sea, of course. My bad for bringing it up in the first place.

nope both rudders down & about 1/3 D/B

J
PS if u watch the vid u can see the bow pointing in all kinda directions as she rides the swells was hard to control with bertrands small 15" wheel , I was steering the boat shooting the vid & controling all the rigging while bertrand sat in Ah! drinking a beer

J
PS when filming from onboard u really need a big lens to really see the size of the waves & swells

Well, in my relative ignorance of sailing the 26M this interests me Highlander. You were hitting close to 10 knots: surely no displacement-hull sailboat under ~100' is going to match that. Yet Mac owners on this site have recently been saying (with regard to the Mac being a mixed power/sail vessel) things along the lines of, 'of course you won't beat a regular (displacement-hull) sailboat'.

You were 'running' to achieve this speed ... but then many sailors switch to motor when the wind is against them, so 'running' is very relevant. And my own limited experience is that, in light winds (which is typically what we get here except in winter), just with mainsail I have passed bigger diswplacement-hull sailboats.

Would you have yanked the rudders and keel in flatter water conditions to get more speed?

Kittiwake

Kittiwake wrote:Well, in my relative ignorance of sailing the 26M this interests me Highlander. You were hitting close to 10 knots: surely no displacement-hull sailboat under ~100' is going to match that. Yet Mac owners on this site have recently been saying (with regard to the Mac being a mixed power/sail vessel) things along the lines of, 'of course you won't beat a regular (displacement-hull) sailboat'.
You were 'running' to achieve this speed ... but then many sailors switch to motor when the wind is against them, so 'running' is very relevant. And my own limited experience is that, in light winds (which is typically what we get here except in winter), just with mainsail I have passed bigger diswplacement-hull sailboats.

Would you have yanked the rudders and keel in flatter water conditions to get more speed?
Kittiwake

Katzenjammer: Because of the Mac hybrid features, it is possible to more easily approach plane when running than any other displacement sailing hull. That would explain the Mac's often reported 10kts occurring on a much higher frequency basis.

Don't quite understand point two?

I agree with pulling keel, while running, in a flat sea condition - under sail. Not the rudders though (while under sail, obviously). This still begs the unanswered question from an earlier, different post. 'If you had a following sea condition, where the hull speed significantly exceeded 6kts' - would you still leave the rudders down at a risk of damage, to retain necessary control?
I think this scenario would rule out trying to do much other than to maintain the status quo.

Ross

Crikey wrote:

Kittiwake wrote: ...
["point two"] You were 'running' to achieve this speed ... but then many sailors switch to motor when the wind is against them, so 'running' is very relevant. And my own limited experience is that, in light winds (which is typically what we get here except in winter), just with mainsail I have passed bigger diswplacement-hull sailboats. ....
Kittiwake

Katzenjammer: Because of the Mac hybrid features, it is possible to more easily approach plane when running than any other displacement sailing hull. That would explain the Mac's often reported 10kts occurring on a much higher frequency basis.

Don't quite understand point two?

I agree with pulling keel, while running, in a flat sea condition - under sail. Not the rudders though (while under sail, obviously). This still begs the unanswered question from an earlier, different post. 'If you had a following sea condition, where the hull speed significantly exceeded 6kts' - would you still leave the rudders down at a risk of damage, to retain necessary control?
I think this scenario would rule out trying to do much other than to maintain the status quo.

Ross

Ah. As to "point two": I was just suggesting that, being a good boat for running with the wind is not an irrelevant positive feature - especially for the casual sailor.

And I had the impression that one could 'sled' downwind using sail control to steer to some extent.

Kittiwake
Katzenjammer eh? Hm, I like it as translated from old high German. But it doesn't match well my style of peaceful boating.

Kittiwake, just tryin to gybe you man - nothin serious. Especialially coming from a schmarotzer like me!
Absolutely with the running sledding under sail control, as others have mentioned. However, depending on conditions, sail may not be a viable option and rudders probably should be present in either case, regardless.
Alles in ordnung.

R

I was seriously thinking that Katzenjamer would be a great boat name; but then I'd have to put a little acknowledgement underneath: 'I'd like to thank Crikey for ...'.
I keep bumping into non-birder boaters who think Kittiwake must be a play-on-words by a guy from Kittimat BC, or an indication that I am a cat lover ... sigh. A guy has to be careful choosing a boat name. Maybe I should have picked Puffin or Duck or something ... but kittiwakes look amazing out over the sea.
Kittiwake

Kittiwake wrote:Well, in my relative ignorance of sailing the 26M this interests me Highlander. You were hitting close to 10 knots: surely no displacement-hull sailboat under ~100' is going to match that. Yet Mac owners on this site have recently been saying (with regard to the Mac being a mixed power/sail vessel) things along the lines of, 'of course you won't beat a regular (displacement-hull) sailboat'.

You were 'running' to achieve this speed ... but then many sailors switch to motor when the wind is against them, so 'running' is very relevant. And my own limited experience is that, in light winds (which is typically what we get here except in winter), just with mainsail I have passed bigger diswplacement-hull sailboats.

Would you have yanked the rudders and keel in flatter water conditions to get more speed?

Kittiwake

Yes in calmer waters just one rudder maybe but if u check out the aft. wake in the vid if u did not see the prop u would think we were under power coming over & down the swells