How fast ?

[kadet]

Yeah I noticed he was talking about an S shortly after I posted

However don't kid yourself that an S is a pure displacement hull. Given its weight and water line length I think they should be termed a semi-displacement hull like most modern fibre glass trailer sailers without full keels and loads of lead. Hull speed is generally predicted by the formula Anthony Deane worked out in 1670 for British Men O'War, Hullspeed(in knots)=1.34*(LWL^1/2), (LWL is hull length at the water line)

If your speeds ever exceed the theoretical speed for a displacement hull then you have a semi-displacement (S) or planing hull .

I have seen a 36ft keel boat (6.9 knot hull speed) under tow by an overeager coast guard crew traveling at 12 knots after a break down. It is a big hole they climb out of but if you give anything that floats enough power it will plane.

One of my favorite destroyers is only 437 feet long and according to Deane's law can only achieve 24.5 knots but in reality can exceed 33+ knots.

A more accurate way to determine speed maybe Froude's Law concerning the characteristics of ship design and the speeds which can be achieved.
see http://www.sjsu.edu/faculty/watkins/froude.htm

[JoeVacs]

I was on a Knox class Frigate in the Navy. It was 438 ft overall. LWL was probably less than 425ft but she would do 30 knots. I know this because my station was on the helm, and we did sea trails 4 times while I was onboard and pushed her to the limit. The military equipment on ships is calibrated regularly, and is some of the most accurate.

[Sumner]

Now I know why the carrier I was on could go so fast and outrun the support ships, it was loooooooooooooong . When we got out of dry dock and went out for sea trials with no aircraft on board I could not believe what that ship was capable of. It would heel over so far that we were dragging the elevators in the water .

Here is some interesting reading on the displacement vs. speed vs. length thing......

http://en.wikipedia.org/wiki/Hull_speed

Using the higher number they also quote 7.3 knots for an S would be possible and they do go into the discussion a little that it isn't as easy as just saying it is a displacement hull and there is more to it than that, like Kadet mentioned.

Also an interesting discussion that has gotten into speeds for S and D's over here.....

http://forums.macgregor.sailboatowners. ... p?t=115085

After reading the posts here and above I believe that given the right circumstances the S or D can exceed theoretic hull speed by a fair amount.

c ya,

Sum

Our Trips to...

Our Mac Pages

Mac Links

[Steve K]

Hi all,

Haven't posted in a long, long time.

Just wanted to comment on this.
1. My Dboat will do 10 knots (consistantly) with the 8hp outboard. (full throttle)
2. I have been double digit speeds, under sail several times.
3. I think the S & D boats ARE a semi displacement hull design. I believe Roger mentions it in the advertisement video.

4. When the boat is in the groove and everything is just right, I'll do between 7 and 9 knots and can set the tiller tammer and go sit on the bow, if I want, while the boat sails herself. And, I mean long enough to get a chapter in on the latest book I happen to be reading.
You may think this is bull, but it's true.

If you examine the hull, you will note that it is indeed round towards the front. However, it's more like a deep V hull towards the rear. This is condusive to planning. Right? My Catalina 22 was very round on the bottom throughout it's full length, but the 26D has a big V shaped from the stern to the companionway. This was designed into the hull so it would tend to plane at higher speeds.

It's a great feeling for me when the boat climbs up over the bow wave and starts to plane a little. Seems to me the magic number is around 8.5 knots. Once you hit 8.5, getting to 10 is not to difficult. You need a consistant breeze, but not too much chop and this doesn't happen all that often.

I think calculated hull speed is just a guideline. It's not a wall that no boat can overcome.

On a side note, I love the way the Dboat glides through the water, barely leaving a wake. My X boat made a lot of churning water noise, whenever it started moving.

One of these days I'll turn my Dboat over and give her bottom a nice race finish, like I've always done my other boats. Can't wait to see how she'll perform without all that lumpy bottom paint on her hull.

Can't understand why a guy will buy a brand new boat with a beautiful, smooth bottom, and can't seem to wait to foul it up with a paint roller, when he keeps it on a trailer.

So, this will be boat number 4 that I will have made right again, on it's bottom. Getting tired.... guess I,ll keep this one.

Anyway, my 2 cents. Sorry if I rambled some.

[madguy]

To Steve.

I just wanted to say thanks....i was getting the impression that people were slightly disbelieving me....

Thinking about your comments i should also add to what i said....

I have recently adjusted and tightened my rigging tension and is now very tight to appox 15-20% tension with a 5 deg rear rake at mast top.
My hull is shaped as you say and it has never been antifould as it lives on the trailer...a few months ago i got the electric polisher out to run over the sides and decided to run it over the hull as well as it was looking a little grubby,, now its gleaming white...

The water that day was very strange and i had never seen like that before....even though the wind was blowing so strong the wind was over 8 feet from the surface...and the surface of the water was very still and calm..

Also i run a 8hp engine two stroke engine (which i lift out of the water when sailing) and have seen over 8 knots when under motor.

So again thanks.

Madguy

[Steve K]

No worries Madguy,

My rig is quite tight also. Only thing is, my mast has almost no rake, at the moment. I'm not sure this is exactly where I want it.. still experiementing. The boat doesn't try to round up and the rudder is usually on the centerline. This is good. However, The lack of mast rake can effect down wind performance, to a degree. (There's compromise in all aspects of sailing)

For info sake:

I have a loose foot, full batten mainsl and stock headsails (a110% and a 150%). I also carry a drifter that I made from a sailrite kit. It's a .75oz, 160%. I use very light, very strong sheets for the headsails (expensive but worth every penny)

I cut the old "popcicle stick" rudder apart and re-formed it. The leading edge is now about 2.5 inches in front of the pivot point. The foil length is several inches longer and is cut off flat at the bottom, just like the dagger board. The foil is a true NACA 012 shape. The result is great steering response and control and very high pointing. The load on the tiller is next to nothing but still has good feel. I plan to take a mold from this rudder and layup a new one from scratch. (it will be stronger, yet lighter than the modified one)

Tip:

I've heard people say their boat gets squirrelly, or wallows when running (downwind run) very fast with spinnaker. Try pulling up the daggerboard (or centerboard). Not only does wallowing stop, but it is easier to keep the boat pointed down and reduces the possibility of a suprise gibe. (although you must continue to be watchfull for this)............... Just thought I'd throw that in. With the right conditions, the boat definately planes in this mode.

[Steve K]

BTW Madguy,

Siince you have a nice clean hull, try this;

http://www.auroramarine.com/aurora/cata ... index.html

VS721clear bottom coat. It was formerly called Aurora HP Bottom Wax.

I,ve used this on all my other boats an believe it is a plus. Can't wait to be able to try it out on my Dboat.

Do the hull and foils.

Best Breezes

[Newell]

Hi Steve and all Mac sailors,

I love stories and more stories and comparisons about fast D models, how come no-one defends the S models against the D? Do you really think the difference is the open slot?

I actually made a 2 slot covers for my X without marked improvement. Though, admittingly, the X is a different type.

Newell
Fast Sunday 96X Windancer 89D

[Steve K]

Some proof
I found this pic of my Dboat, sailing along by herself. I took the picture (I was the only one onboard).
You may be able to spot a little tiny boat in the background. This is a 26X I passed earlier and yes, I was sitting on the bow pulpit, or walking around on the foredeck the whole time.
The wind had calmed some, so no, I'm not doing claimed top speeds here.
Oh and btw, the lifelines have been re-installed.

http://www.box.net/shared/t749sfc1t4

[Steve K]

Oh, and I forgot to mention, notice the lack of wake. She really slips through the water

[Highlander]

Here's my sailing along by herself
http://s78.photobucket.com/albums/j95/m ... 010020.flv

http://s78.photobucket.com/albums/j95/m ... 010021.flv

J

[Newell]

Steve,

I blew up your picture but couldn't tell if that is my X in the background. One thing for sure is that Highlander has more money invested per sq ft than you and I combined, with 3 boats between us. However, it's likely true that the more you put in, the more you get out of it.

Newell
Fast Sunday 96X Windancer 89D

[Steve K]

Hey Newell,

Are you coming to Mead in March?
Bringing the D or th X?

Got news..... I'll PM you.

[grady]

Hi Steve and all Mac sailors,

I love stories and more stories and comparisons about fast D models, how come no-one defends the S models against the D? Do you really think the difference is the open slot?

I actually made a 2 slot covers for my X without marked improvement. Though, admittingly, the X is a different type.

Newell
Fast Sunday 96X Windancer 89D

I do not think the slot makes that much difference ether. It has to add a little drag but not that much.

I have not looked a a D model in real life but I have looked at my S model and am convinced that the difference is the fact that the S model center board is loose enough to turn sideways when extended (OK maybe a little exaggeration). I think if you would make the centerboard rigid when extended there would be almost no difference between the S and D models. At least that is my opinion I will let you know if it is true this summer.

[Sumner]

UNITED STATES PERFORMANCE HANDICAP RACING FLEET

The following pages list low, high and average performance handicaps
reported by USPHRF Fleets for over 4100 boat classes/types.

..................................low...... high....average
MACGREGOR 26S............. 210...... 258...... 222
MACGREGOR 26D............. 210...... 219...... 213
MACGREGOR 26X............. 216...... 273...... 228
==========================================

From those it looks like they rate the S and D pretty close with a 7 second difference over a mile. The S did have some high ratings though quite a bit higher than the D. According to 'them' the X wasn't that bad. Seems I've seen worst numbers for the X. They didn't have any numbers for the M.

For us it makes no difference as we are cruisers. We for sure wouldn't want to give up the swing centerboard. It has bailed us out more than once,

Sum

Our Trips to...

Our Mac Pages

Mac Links