Forum Home
IntroductionBrowse
Our MacGregorExploringArticlesAbout this Website
ManualsDealer InfoSailing LinksTell a FriendSupport this Website
Forum Home
Boomkicker Banner

speeds

A forum for discussing topics relating to older MacGregor/Venture sailboats.

Moderators: tangentair, beene, Heath_Mod, Hamin' X, kmclemore, Catigale

speeds

Postby Interim » Mon Jun 11, 2018 9:50 am

I tried out my new sails this weekend, and was a little frustrated I didn't hit the theoretical hull speed (which I think is just under 6.5knts for a 26S). We peaked at 6.1 on a beam reach, with winds 10-12 mph.

Do any of you have a sense if that is "normal" in those winds? Should I be able to get more out of it? Or do I need more pressure to get the big numbers?

--john
Interim
Engineer
 
Posts: 163
Joined: Thu May 08, 2014 9:31 am
Location: Great Plains
Sailboat: MacGregor 26S

Re: speeds

Postby paul I » Mon Jun 11, 2018 10:52 am

Low 6's is the best my :macx: has ever done under sail, and its a rare day that it does that.
paul I
First Officer
 
Posts: 405
Joined: Tue Jul 19, 2011 7:43 am
Location: Niagara Falls, NY 2000 26X w/Honda BF50 "NoneShallPass"
Sailboat: MacGregor 26X

Re: speeds

Postby sailboatmike » Mon Jun 11, 2018 5:44 pm

A couple of things here.

1) New sails need to break in, they are pretty much like over starched sheets until they break in, so you cant get the best sail shape.

2) New sails will not make up for other things that are wrong, over weight, incorrect crew positioning, poor foils, increased drag because of build up on the hull, sails not balanced so using to much rudder input and many other things.

In theory the 26X and M should plane under sail (Roger mentioned 17knts for the X) but in reality it will never get there for many reasons but mainly due to weight
sailboatmike
Admiral
 
Posts: 1524
Joined: Fri Mar 13, 2015 12:17 am
Location: Australia
Sailboat: MacGregor 26X

Re: speeds

Postby Freedom77 » Mon Jun 11, 2018 6:09 pm

Agree with Paul I and Sailboat Mike. Hull speed is theoretical, like wind tunnel test under ideal conditions. Lots of factors involved. Best we ever did was sailing downwind to Ensenada Mexico with following sea and spinnaker. Hit 8+ knots. WOOO... Fair Winds and Full Sails...Old Salt.
User avatar
Freedom77
First Officer
 
Posts: 406
Joined: Sun Nov 14, 2010 12:43 pm
Location: Lake Mead, Nevada '76 V-25 #928
Sailboat: Venture 25

Re: speeds

Postby Tomfoolery » Mon Jun 11, 2018 7:21 pm

Freedom77 wrote:Agree with Paul I and Sailboat Mike. Hull speed is theoretical, like wind tunnel test under ideal conditions.

And even the 1.34 speed to length ratio (S/L)* is just a generic value, and will vary based on the W/L ratio (weight to LWL), and even then it's subject to some uncertainty. But it explains, in part at least, how racing shells can go much faster than their theoretical hull speed would suggest, based on the 1.34 S/L value.

*HS = 1.34 x sqrt(LWL) where 1.34 is the S/L value, which is by no means universal
User avatar
Tomfoolery
Admiral
 
Posts: 4982
Joined: Tue Jul 05, 2011 9:42 am
Location: Rochester, NY '99X BF50 'Tomfoolery'
Sailboat: MacGregor 26X

Re: speeds

Postby sailboatmike » Mon Jun 11, 2018 8:01 pm

Tomfoolery wrote:
Freedom77 wrote:Agree with Paul I and Sailboat Mike. Hull speed is theoretical, like wind tunnel test under ideal conditions.

And even the 1.34 speed to length ratio (S/L)* is just a generic value, and will vary based on the W/L ratio (weight to LWL), and even then it's subject to some uncertainty. But it explains, in part at least, how racing shells can go much faster than their theoretical hull speed would suggest, based on the 1.34 S/L value.

*HS = 1.34 x sqrt(LWL) where 1.34 is the S/L value, which is by no means universal


Most racing boats are not really true displacement hulls, they are sort of semi displacement hulls, if you look you will see most have a wedge shape, thin at the bow becoming wider all the way back to the transom (I believe its termed as "Fine Entry")

They are also generally have minimal V shape at the rear, the idea being that less boat in the water equals less drag and of course the big one is they are VERY light. On the occasions I race I know I don't have much chance just because I'm over twice as heavy as many of the boats we sail against, some of them weigh in total at not much more than just our water ballast weighs, never mind the actual boat, motor, fuel etc.
sailboatmike
Admiral
 
Posts: 1524
Joined: Fri Mar 13, 2015 12:17 am
Location: Australia
Sailboat: MacGregor 26X

Re: speeds

Postby Interim » Tue Jun 12, 2018 1:18 pm

Thanks for the comments, all.

I think what may be frustrating me is that I had an O'Day 16ft that could hit 7.5 when it planed, beating my 26s by more than a knot.

We'll see what stronger wind brings, and probably trying a broad reach. I'm not a racer, but I do take speed as an indication of how well we have the boat set up.

--john
Interim
Engineer
 
Posts: 163
Joined: Thu May 08, 2014 9:31 am
Location: Great Plains
Sailboat: MacGregor 26S

Re: speeds

Postby sailboatmike » Tue Jun 12, 2018 10:41 pm

Interim wrote: I'm not a racer, but I do take speed as an indication of how well we have the boat set up.
--john


I would take ability to sail to windward as more of a indication of how well the boat is set up. I'm just wondering how you were measuring speed, is that speed over water or speed over ground. I know my boat log reads very low in comparison to my GPS.

As far as I can see the 26S is a true displacement hull and will never plane as such were as the ODay 16 is just a dinghy with sail area that is proportionally much greater(Im presuming the day sailor), it is not hauling around the weight that a 26 does as dinghies don't in general have any or very little ballast.

I have a FJ (flying Dutchman Junior) in my front yard, I would never expect my X to go anywhere near the speed that thing can develop, however the FJ is a very wet ride and if the X had to have the proportional sail area the mast would need to be at least 40 feet high and at least 6 big bloke hiked out to windward
sailboatmike
Admiral
 
Posts: 1524
Joined: Fri Mar 13, 2015 12:17 am
Location: Australia
Sailboat: MacGregor 26X

Re: speeds

Postby dlandersson » Wed Jun 13, 2018 5:33 am

Mid 5's sailing to windward (60 degrees) is the est I've ever seen. 8)

paul I wrote:Low 6's is the best my :macx: has ever done under sail, and its a rare day that it does that.
User avatar
dlandersson
Admiral
 
Posts: 3222
Joined: Fri Aug 27, 2010 12:00 pm
Location: Chicago metro, USA
Sailboat: MacGregor 26X

Re: speeds

Postby John McDonough » Wed Jun 13, 2018 3:00 pm

paul I wrote:Low 6's is the best my :macx: has ever done under sail, and its a rare day that it does that.



Paul. if that my former 26-x I was I reaching speed of 10.5-11 knot surfing in 3`-4` waves.

That was leaving Erie and heading past long Point Canada on to Port Dover with an empty ballast tank and cruising spinnaker the whole trip.

Myself at the wheel with 2 well conditioned friends as portable ballast.

Even if my speed indicator and GPS was wrong I made it from Erie to Port Dover Canada in less than 5-1/2 hours.

With motor at full throttle in a dead calm I could make the same trip in about 3-1/2 hour.


PS How is that boat holding up. :?: I tried to contact Bud a few times. He might be in bad health. :?:
John McDonough
First Officer
 
Posts: 416
Joined: Thu May 26, 2005 10:57 am
Location: pittsburgh pa..2000-26X--Honda50


Return to MacGregor/Venture Discussion

Who is online

Users browsing this forum: ncartercalfrac and 3 guests

Copyright 2004 - 2018 © HK Innovations