Bad performance beating

[seahouse]

Hey Vizwiz!

Well spoken. And I’d like to second that line of thinking.

Since the design of the Mac hull is different than conventional sailboat planing hulls, some of the performance principles might not translate well from one to the other. So it’s quite conceivable that upon the approach of plane there might be some inherent advantages that conventional hulls won’t have.

Hmmm. Two interesting things now. This, and the creation of quark-gluon plasma.

- B.

[ROAD Soldier]

ROAD soldier -
Be real interested if you could photo your cutter rig or storm sail and how the rigging is done. I have a 26d. I see where what you say could be useful. How is it in heavy seas? Out here we get low 1-3 ft seas and 5 knot winds or greater winds and 5-6 ft rollers occasionally +. Some of you guys' photos make us jealous of the 20 kt winds and essentially no real swells! When you come off a 6 ft roller at an oblique angle you may be fighting that with the rudder to stay on course, timing for the next 6-10 sec later.Curious if your storm sail helps the boat maintain course as the lower sail portion in the valley of the swells loses its wind temporarily then re catches, then loses...adjust rudder .. yada .. yada..
Thanks,
CB
(another ex Army puke)

If you want to know how it is set up, check (Two Head Sails) topic in rigging. Now for heavy seas just like all Macs they buck like wild mustangs in any configuration, However I do find that letting 1/3 of my Genoa out will give a headsail up high to maintain some grip with the wind and aims it slightly downward. This give the storm-sail something to latch on to. I also have Ida Rudders good stuff. Now for your swell situation find a bay that doesn't have it to set personal speed records. Plus swells are not so bad at least you can still sail when they become breakers forget it the only things used there are good rudders, good ballast, a storm-sail only for stability, and a good engine Mac's do not slice through any wave, just ride over or get smacked hard sideways or backwards by a breaker if you try to strictly sail in the 5ft or higher ones.

[Catigale]

Im not sure i agree with the half planing speed theory there viz....the critical event in transitioning from displacement mode to planing is the lifting of the bow....until this happens ( which i. Think is well over 6 kits) I don think you have any force lifting the hull to the surface other than buoyant forces.

[vizwhiz]

That's okay Cat, I wasn't suggesting you'd get on plane...I was just trying to point out the fact that there are issues with using displacement hull theory on a planing hull... The hull lifts as a matter of total force distributed underneath the projection of the area facing straight down...there is a vertical component to the forces of the water on even the pointy part of the front of the boat... As the boat moves, the bottom surfaces of the boat impinge on the water - they are designed so that the back of the boat sits a little lower than the front - it's a ramp or wedge before you even start - the planing part of the hull is relatively straight/level/flat, but the part leading into it is not - kinda like driving your boat onto the trailer.

But the transition you are talking about is not technically required - it has to do with getting the boat bottom at a higher angle of attack and is more a phenomenonenomonenon that occurs than it is a design thing - but I'd have to get really specific about it and I just got done trying to explain displacement in another thread, so I'm gonna just ask for a bye on this one for now... please? Maybe later?

However, I WAS thinking about it last night, and remembered that Mr. MacGregor said in his M video that flying the big spinnaker you could actually get the M up to planing speeds...anyone on here ever done it? I'm curious, because that represents a lot of horsepower! Woo hooo!!

[Highlander]

vizwhiz
And Highlander, I'd like to buy a license to cutter-ize my S when I get it.

No Problem ! Just go to one of my Photobucket sides & pm when yer ready be glad to help
can save you a lot of greif

J

[Highlander]

Here's running in 1 meter waves later building to 1 1/2 meters no problem , I have sailed in 12ft to 15ft swells a lot of fun but also a lot of work if sailing single handed
http://s844.photobucket.com/albums/ab1/ ... 0_2495.mp4




J

[ALX357]

An M might sail satisfactorily with just the main, but the X definitely has to have a foresail to make it thru all points of sail.

'Next to impossible to tack with the main only, you'll run up in "irons" every time. In fact the X can sail with the Genoa alone, if done carefully. It is still a bit more difficult to tack, but it's better than with the main only. Best is both foresail and main together, for the X.

[vkmaynard]

When we first got our boat we "accidentally" sail across the Neuse River NC in a Nor'easter (not paying attention to the weather). We occasionally hit 8 MPH with just the Genoa on a broad reach for about 15 minutes. That party ended when the boat nearly broached due a large beam wave (lots of chop in that river). We quickly furled the Genoa and white knuckle motored in following chop to safety, breaking a rudder.

We were the only small boat out there. The few other larger sailboats were motoring across. The destination marina could not believe we had just crossed from Oriental NC to Seagate Marina in those conditions. Not to be repeated (except for the Chesapeake trip last year, not as much wind).

What is hull speed on an X when a 90 Hp motor will push it at 31 MPH?

So I believe Ron’s numbers when I saw first hand what the boat will do (don’t want to have Ron down here “taking care of business").

Victor

[ROAD Soldier]

Ok gentlemen bare with me I am now just joining the 21 Century with this video stuff. As promised here are my videos from Saturday the 27th November 2010. I just found out today I could have made them better because my phone has different resolutions on the camera. So next time they will be better so for now you will have to deal with Neanderthal Video Works showing first on a beat then a Broad Reach to a Beam Reach with two head sails on my 26X. Also on the second video it sounds like I said 50MPH winds when I really said 15MPH.

Beat Video
http://www.youtube.com/watch?v=WbJtGF-qd3M

Broad to Beam Reach Video
http://www.youtube.com/watch?v=mxRT1Heo9og

[vizwhiz]

What is hull speed on an X when a 90 Hp motor will push it at 31 MPH?

I think this is the illustration I was needing for my earlier point (Catigale)...you can't apply displacement hull theory directly to this hull...again, that doesn't mean I think it defies physics...it just has a slightly different set of physics in its pocket.

[Catigale]

Yeah but.....

I think there are three modes of operating a Mac hull....displacement mode, transition and planing.

Under 5 knots - displacement - I agree that there can be some lift here depending on angle of attack.

30 knots is definitely planing

where the transiton begins and ends usually causes a fight on the Board, so Ill say somewhere between 5 and 30 knots..just to play Switzerland....

[vizwhiz]

You pulled out your henweigh...I saw you!

[Catigale]

Its a henweg in Swiss....

[beene]

!

beene:

Ok Gentelmen. This thread was packed with posts from 2 members that violate the rules of this forum found here: http://www.macgregorsailors.com/forum/v ... f=6&t=4747. I removed the thread, deleted any posts that go against Forum rules, and am now re-posting it. This thread is full of good info and dialog between forum members, so I thought it was worth the effort on my part to clean it up and re-post it. Please keep posts within Forum guidelines in the future. Fair winds. G

[J.Teixeira]

Hi Highlander



Is it water coming down from your Genoa???

Or is it Scotch W Optic Illusion

Jose