Double ender designs slow

[adam stevens]

I am specifically speaking about Colin Archer designed pilot boats from late 1800's to early 1900's. I hear complaints of these designs (as well as other CA inspired double enders) being extremely slow. They are heavy and full keeled but are double ender designs inherently slow for other reasons? English pilot cutter designs are also heavy and full keeled but seem to not get as bad of a reputation as the Norwegian double enders in terms of speed. Obviously they are all slow compared to light weight modern day designs and construction materials but I am wondering about comparisons between the English and Norwegian pilot cutter designs. Thanks

 

[bajansailor]

Welcome to the Forum Adam.

I think the main reason why they are considered to be 'slow' (relatively) is that they are very beamy (low L/B ratio), very heavy (high displacement / length ratio), with conservative sail area / displacement ratios while being pretty 'full' in the midships section.
I have sailed on a ferro cement Colin Archer derivative many moons ago - 39' on deck and 19 tons displacement. Yes, she was 'slow' - in winds less than say 15 knots. But she could easily carry full sail in 20 knots, and she would stomp along happily when other boats would be reefing.
I think that maybe the English pilot cutter are not so extreme in their hull form, with finer ends.

 

[BlueBell]

Welcome Adam S.

Slow, maybe, but they used them for a reason.
I don't care how slow a boat is if it gets me home in a storm.
Seaworthy is a word that comes to mind.
Cheers

Edit: Sorry, I didn't answer your question.
No, double enders are not typically or inherently slow.

 

[Will Gilmore]

I have always known double endeders to be particularly easy sailers. At or bellow displacement speeds, the stern moves the water very easily off for less turbulent release.

They can have other problems from slightly reduced aft flotation that can allow for squatting near or above hull speed and they naturally have more rocker than a square transom, but a well trimmed and balanced double-ender can sail extremely well.

-Will (Dragonfly)

 

[fastwave]

Bob Perry-designed double-ender Sliver http://sailingmagazine.net/article-1664-bob-perry-designed-double-ender-sliver.html

 

[Dolfiman]

Double-ender option should not automatically associated with heavy blue water designs, Ray Hunt explored a lot the double-ender option for light racing sailboats with its 201, 401 and 501 designs , competitive in those days :
C. Raymond Hunt International 210 - Classic Sailboats http://classicsailboats.org/portfolio-view/c-raymond-hunt-international-210-class/
C. Raymond Hunt International 410 - Classic Sailboats http://classicsailboats.org/portfolio-view/c-raymond-hunt-international-410/
C. Raymond Hunt International 510 - Classic Sailboats http://classicsailboats.org/portfolio-view/c-raymond-hunt-international-510-class/

The Sliver quoted above by Fastwave is in line with these light fast double-enders,

 

[Waterwitch]

Comparing Bristol Channel pilot cutter plans to a Collin Archer, the Bristol is long and lean, so a faster hull form. http://www.colin-archer.no/ColinArcherPlans-filer/image004.jpg
https://i.pinimg.com/originals/37/53/a8/3753a84a0b5580013c48391e3512b247.jpg

 

[gonzo]

If you want to compare a Colin Archer to faster designs that can actually sail upwind, check designs by German Frers (senior) and Manuel Campos.

 

[philSweet]

See also the designs of Albert Strange for a look at boats contemporary with Archer's

 

[sharpii2]

...
They can have other problems from slightly reduced aft flotation that can allow for squatting near or above hull speed and they naturally have more rocker than a square transom, but a well trimmed and balanced double-ender can sail extremely well.

-Will (Dragonfly)

I don't see why a double-ender would have more rocker than a transom-stern boat. I would think it would be the other way around.

A transom stern boat needs to carry its transom above the WL. A double-ender has no such requirement. One I designed has its stern-post about three inches under water. This is intended to discourage broaching, and also to limit the rocker of the keel son.

One design I played with would have the top of the stern post higher than the top of the bow one, as this design would be sailing down wind much of the time.

I think the double-ended is best for slower boats, which are likely to be menaced by following seas. But the stern-post had better be high.

A disadvantage of a double-ender is that it needs a fuller bow to get the same amount of sail carrying ability as a transom-stern boat with the same beam and same ballast placement. All the more reason to pick this plan-form for a boat designed to sail at hull-speed or less.

It will typically have less deck area and less room down below than a more modern transom stern boat.

 

[Will Gilmore]

I don't see why a double-ender would have more rocker than a transom-stern boat. I would think it would be the other way around.

A transom stern boat needs to carry its transom above the WL. A double-ender has no such requirement.

Good point.

I was looking at it from a pitching point of view. Even with the stem below the waterline, there is less flair to increase floatation as it sinks, where a square transom has lots of submerged flotation once it begins to pitch. Of course, the fullness and shape can be manipulated in the design. It doesn't have to be a fine stern to be a double-ender.

-Will (Dragonfly)

 

[Velsia]

We have to remember that speed is relative in sailing. As an example, nearly everything available to us mere mortals is slow compared to the Ultimes.

Here was double ender noted for her speed
STORY OF WHIRLWIND http://www.america-scoop.com/index.php/en/30-2/whirlwind/1346-story-of-whirlwind