Canoe stern vs ????

[boatman61]

Originally Posted by Kettlewell

I rather like the way our old boat Snow Star looks.

[Lee Jerry]

Originally Posted by rslifkin

For the hobbyhorsing issue, a boat with relatively balanced ends is the worst case.

I'm not sure why you say that; it isn't obvious to me why it would be. Do you have a reason(s) or reference for that claim?

A wider stern means the stern goes down less for a given amount of bow rise.

And it means that the stern is forced upwards more (and the bow down more) when the wave passes under the stern.

This shifts the center of rotation in pitch further aft relative to the center of gravity. That gives more damping to the pitching motion, so the boat will still pitch, but it won't hobbyhorse as readily and you'll also feel less vertical motion in an aft cockpit (more comfortable).

The stern being forced up (referenced above) seems to make it a jerkier motion, hence the "less harsh" description used previously.

In general, I think that effect of (dynamic) buoyancy distribution is similar to the effect of weight distribution - in the ends is bad and makes hobby-horsing worse. A wide stern shifts buoyancy aft, therefore bad for HH.

[Bill O]

Do not disagree with the general comments about the canoe stern.

1. Yes, you do loose space to store things. One adjusts.
2. It does look nice.
3. Utilizing the full lwl is helpful when motoring or lighter air sailing vs a long overhang hull design. (It can exceed hull speed when surfing)
4. Fishing off the stern limits the number of lines and rig spread (we still catch plenty of fish)
5. In some conditions it can hobby horse. IMO this is due to the lack of surface area to stop the momentum once it starts vs. the wider stern.
6. There was some discussion of added buoyancy in wider sterns. With the bonus space, the tendency is to overload them. Once overloaded with too much weight/stuff it can negate this additional buoyancy and can also induce hobby horsing.

[Kettlewell]

So the waves WILL be passing the boat at most times. So most of the time the stern has to act a bit like the bow….split the wave.

That seems to me to make the canoe stern (or high wineglass) invaluable. Or at least makes the boat much more comfortable?

I have not sailed a modern fat-transomed boat offshore, but I have sailed boats with both a traditional canoe stern and a moderate traditional transom. It really depends on the design of the whole how well they perform downwind. Getting back to storage on the stern, I think a lot of modern boats do suffer from way too much windage back there: dinghies, cockpit enclosures, solar panels, other junk, and in strong winds that will not help with steering, pitching, etc. The worst shape, IMHO, was the trend back in the 50s and 60s to have short waterlines with long overhangs on both ends. Makes for some pretty boats, but they tend to pitch horribly, not steer well downwind, and be prone to sailing on their ears when headed upwind. Probably fine in bigger sizes, but I don't like them for cruising. Our double-ender, Snow Star, was the most comfortable boat offshore we have ever owned. No pitching, steered easily downwind, made good overall speed, could sail herself for hours if you got her trimmed right. I could lock the wheel, go below to take a leak, and come back up on deck with her right on course when headed to windward. OTOH we had a small transom-sterned custom design that was also fantastic offshore and would surf off under complete control. We made over 10 knots on several offshore runs which is moving out on a 30-foot cruising sailboat loaded down with stuff. She had a big rudder on a skeg and the faster we went the better the steering got. The transom meant she didn't squat badly at higher speeds, and I think contributed to keeping her from rolling downwind.

[Lee Jerry]

Originally Posted by Benz

Everyone is comparing canoe sterns to "wide, modern transoms." Well, of course canoe sterns are better than that. But there's no context in which a canoe stern is better than a transom on a full-keeled cruising boat. I have thousands of miles logged on various full-keeled transom-stern boats, and what makes them behave well in a following sea is the keel. The underwater profile of a well-designed full-keel boat will be the same whether it's got a canoe or a transom--the only difference is that canoe sterns are an ugly affectation (IMO), that take away valuable space.
Now, beauty is in the eye of the beholder, so no offense to canoe-stern lovers, but I personally don't like the look.

Most things, with the discussion here included, have a smooth transition from one extreme to the other. Therefore, comparing the extremes is easier to make the point. Intermediate points (moderate stern beam / shape) would generally have corresponding intermediate response.

Of course keel and under profile play a part in performance in following seas. But so does the shape of the aft end ABOVE the (static) waterline. If a quartering wave lifts a beamy stern quarter, the boat will act differently than if that quarter was less buoyant and the stern lifted less. Seems pretty obvious to me.

[rslifkin]

Originally Posted by Lee Jerry

I'm not sure why you say that; it isn't obvious to me why it would be. Do you have a reason(s) or reference for that claim?




And it means that the stern is forced upwards more (and the bow down more) when the wave passes under the stern.




The stern being forced up (referenced above) seems to make it a jerkier motion, hence the "less harsh" description used previously.

In general, I think that effect of (dynamic) buoyancy distribution is similar to the effect of weight distribution - in the ends is bad and makes hobby-horsing worse. A wide stern shifts buoyancy aft, therefore bad for HH.

As you shift the center of rotation aft, you get a few changes. You're lifting the keel more to get the boat to pitch, so it's harder to get the boat to pitch. And because there's less vertical motion aft, you feel the pitching less (you get a change in deck angle and see the bow go up and down, but the cockpit feels less vertical motion).

By making it harder for the boat to pitch (because you have to lift the bow more vs just rotating back and forth), you also get less momentum in pitching. That means the boat pitches more in response to individual waves rather than getting into a pattern of hobby horsing as the waves match up with the natural pitching frequency (it can still happen, but not as easily).

[Bowdrie]

Originally Posted by Lee Jerry

they also behave better to weather than many modern clorox bottles. The wide back end drives the bow down, skews the waterplane, lifts the rudder...
That better motion translates to easier steering too, whether a driver, wind vane or autopilot (lower energy consumption).
They have lower drag at low speeds (comparing similar weight), both lower wetted surface and better shape (lower wave making).
They don't "slap" at anchor the way wide, flat ass-ends do.
I would think that they'd hobbyhorse less, or at least less harshly

Valid points.
The "hobbyhorse" issue is a harder nut to crack as the boat gets shorter.
It has much to do with the shape of the buttock lines, as a boat gets longer it's much easier to flatten-out the buttocks in the midship sections.
In shorter boats the buttock lines start approaching the shape of an arc, rather than a more elliptical shape.
This can easily be seen by comparing the lines on a Westsail 32 vs an Alajuela 38, both by the same designer and both having nearly the same beam.
That 6' of length makes a big difference.
Now, the designer of both, William Atkin, did say in one of his writings that the 32' boat would not like to be pushed against a short sea.
Of course, neither is what one would call a "canoe stern", but are true double-enders.
Canoe sterns are more of an attempt to give a double ender a fatter rear end, which can help to suppress the stern wave when the boat gets up to a SL ratio that's over ~1>1.1.
True enough, the flatter rear end of more modern shapes is better suited for higher speeds.

[Lee Jerry]

Originally Posted by rslifkin

As you shift the center of rotation aft, you get a few changes. You're lifting the keel more to get the boat to pitch, so it's harder to get the boat to pitch. And because there's less vertical motion aft, you feel the pitching less (you get a change in deck angle and see the bow go up and down, but the cockpit feels less vertical motion).

By making it harder for the boat to pitch (because you have to lift the bow more vs just rotating back and forth), you also get less momentum in pitching. That means the boat pitches more in response to individual waves rather than getting into a pattern of hobby horsing as the waves match up with the natural pitching frequency (it can still happen, but not as easily).

I'm not convinced.

I think you're mixing some issues and are wrong on others. The boat statically trims about the longitudinal center of flotation, but pitching, and hobby-horsing even more so, are dynamic response to a continually changing buoyancy distribution as waves travel along the hull and the hull pitches and heaves. So there is no one point that is the center of rotation (depending on how fine a "point" were talking about - that point is continually moving fore/aft and up/down).

You are not "lifting the keel more." Is what you are describing different for powerboats of different shapes?

I'm not convinced there's "less vertical motion aft" in total. There may be less "negative" motion (submergence) aft, but I think there is a corresponding (or similar) increase in the "positive" motion - the stern will rise higher when the wave is aft (as I previously said). The general response (buried in all the dynamic movement) will be a slight bow down average pitch.

I think that's enough...

[Cheechako]

Originally Posted by GILow

As a long time canoe stern owner I observe the following:

1. They look kinda salty so everyone assumes you can sail.
2. They reduce the useable space inside the boat more than you’d believe.

Apparently they do some other stuff, something to do with following seas, rough conditions…

But points 1 and 2 cover most of it.

That's my opinion also. I think it's more of a "looks" thing than anything. There's talk about it parting following seas etc. And designers seem to combine a canoe stern with wide full aft sections in the hull. That makes sense to me because my feeling is a non canoe stern would normally lift better than a canoe stern without full aft sections. If you want the stern to lift then a conventional double ender with some overhang would be good.
OP; I would find the boat that best fits what you want regardless of stern shape.

[wingssail]

It seems like many of the comments here are theoretical and not actually demonstrated in reality.

For example the idea that following seas will be "split" when they hit a canoe or double ended stern but would slam into a transom. That might be true if you are looking at the shapes of a pier which cannot move, but on boats it just doesn't happen. Instead, in my experience, in virtually all following seas situations, the boat rises on the face of an overtaking wave and the wave simply passes under the boat. The wave does not "strike" the above water part of the boat. If the former was true then on my boat, with a long sloping reverse transom, waves would come shooting up the transom like going up a ramp and land in the cockpit. That has never happened.

Underwater shape vs above water shape: Many modern hulls have a long, flat, runs aft to increase speed. This is a trend in racing boats which has proven to be effective. It is hard to imagine those broad shapes being gracefully molded into a canoe stern. So this means that canoe sterns cannot be as fast as broad, flat sterns. Speed is fun and it is important to me. I don't like slow shapes.

Tendency for hobby horsing, broaching, etc, these are all theoretical to me, not based on actual experience. There are other factors which influence these behaviors more than the shape of the transom.

[sailorboy1]

I can think of nothing worst on a cruiser than giving up the fold down helm seat and stern access that allows for easy use of the dingy

Bob Perry has said that the canoe stern has no real use and he only did it on the Valiant as a style thing

[Kettlewell]

For example the idea that following seas will be "split" when they hit a canoe or double ended stern but would slam into a transom. That might be true if you are looking at the shapes of a pier which cannot move, but on boats it just doesn't happen. Instead, in my experience, in virtually all following seas situations, the boat rises on the face of an overtaking wave and the wave simply passes under the boat. The wave does not "strike" the above water part of the boat. If the former was true then on my boat, with a long sloping reverse transom, waves would come shooting up the transom like going up a ramp and land in the cockpit. That has never happened.

Ha! I've had breaking offshore waves run right over the boat to the point I was holding my breath in the cockpit and hanging on for dear life. Yes, if you can run off fast enough you should stay ahead of most of the breakers, but if one does catch you with an open transom hopefully you are tethered in and have strong hatchboards. OTOH, not sure a canoe stern will help more than a proper transom stern that is closed. A lot depends on your freeboard, buoyancy aft, weight distribution, etc.

[Cheechako]

Originally Posted by wingssail

It seems like many of the comments here are theoretical and not actually demonstrated in reality.

For example the idea that following seas will be "split" when they hit a canoe or double ended stern but would slam into a transom. That might be true if you are looking at the shapes of a pier which cannot move, but on boats it just doesn't happen. Instead, in my experience, in virtually all following seas situations, the boat rises on the face of an overtaking wave and the wave simply passes under the boat. The wave does not "strike" the above water part of the boat. If the former was true then on my boat, with a long sloping reverse transom, waves would come shooting up the transom like going up a ramp and land in the cockpit. That has never happened.

Underwater shape vs above water shape: Many modern hulls have a long, flat, runs aft to increase speed. This is a trend in racing boats which has proven to be effective. It is hard to imagine those broad shapes being gracefully molded into a canoe stern. So this means that canoe sterns cannot be as fast as broad, flat sterns. Speed is fun and it is important to me. I don't like slow shapes.

Tendency for hobby horsing, broaching, etc, these are all theoretical to me, not based on actual experience. There are other factors which influence these behaviors more than the shape of the transom.

It has happened to me a few times. Canoe stern or traditional stern. Completely dousing the cockpit.

[sailingharry]

A lot of comments above, some reflecting strong personal preference and some probably have real merit. A couple of my thoughts.

I think that my moderate square transom has far more storage above and below than any double ender I have ever seen. It is true that weight in the stern is bad. But I'm not sure what additional space amidships a double ender gives to make up for that lost space in the stern. And if you choose to just not have it aboard, then it adds no weight in the stern of a conventional transom either.

While it is horrible for boat performance, no question about it, my moderate transom allows a wonderful arch with solar panels and bimini and davits. People cruise without these amenities, and some swear against them, but not me!

A swim platform with walk through transom is critical. Non-negotiable for us.

Your choice of underbodies severely limits your choice of boats, and adding a double ender makes it massively more so. Limiting the choice of boats and make it very difficult to find one you are looking for, and limiting to a mostly older set of boats can make it difficult to find one in good shape, add considerably to maintenance and refit issues, and can make it hard and expensive to obtain insurance (not to mention the 20% per year depreciation for every year over 20 years old applied applied to payouts). This does not mean it's impossible, just that you have ruled out well built and seaworthy boats such as Sabre, Tartan many Halberg-Rassey, Swan, Outbound, Saga, and many others. Finding a skeg hung modified fin double ender from this century in good condition will be hard.

[GILow]

Originally Posted by sailorboy1

….



Bob Perry has said that the canoe stern has no real use and he only did it on the Valiant as a style thing

One of the things about Bob Perry is that he pontificates at such great length and frequency on practically everything even vaguely boat related that one can always find he has said something to support any view of boats you care to choose.

This pontification is only enhanced by the number of sycophants willing to repeat his ramblings.