It seems to be the experience of many seasoned cat sailors that lighter catamarans have some appealing characteristics including their acceleration and extraordinary responsiveness (among others). This phenomenon is not unlike an analagous situation between keel boats and dinghies which also are different in mass and responsiveness.

Since everything in sailing is a tradeoff, one might expect any extreme including lightness to have both advantages and disadvantages depending on yor circumstances and skill level. Topics that have already been well addressed on this forum include lightness vs feel, speed, righting, beach handling, etc.

I would expect that a lighter cat overall should be really fun for an experienced cat sailer due to it's acceleration and responsiveness. I would further expect that any cat that is so highly responsive to helm, weight placement, sail trim, etc may also be just as quick to get one into trouble due to minor lapses in technique/skill and/or more demanding conditions.

If true, this would suggest that all other things being equal (ie, modern designs) that a heavier cat would be a more gentle platform for novice sailors because it would be more forgiving in a wide range of conditions. I want to differentiate between a more gentle learning platform and a faster learning platform: a lighter cat may in fact let one learn more quickly due to it's greater feedback but might be more frustrating in the process. It might also restrict sailable days at least intially.

How do people's own experiences correlate with this thinking?

I appreciate the intput!

Jerry

You are pretty much right about everything -- except that you also have to factor in the size and power of the engine, i.e.,the relative amount of sail area, the sail plan (main only or main and jib), height of the mast, etc.

Compare the A-Class cats, which are 18 feet long and now weigh 165 lbs or something anorexic like that (I can never remember exactly), and the Hobie 18, which weighs 450 lbs. (according to the company specs). The A-Class has 150 square feet of sail in main only, and the Hobie 18 has 220 square feet of sail in main and jib. The Hobie 18, at the same length as the A-Class, is obviously a much more forgiving boat. It is not just because it is heavier but because it has a smaller engine relative to the boat's weight.

They are all fast and fun. Some have a wider range of wind speed and wave conditions they (and you) can handle comfortably.

You have the boat scenario pretty much inline but you left out crew weight. Boats don't sail themselves. If you are capable you may be able to sail an extreme light weight without much problem in steady conditions. It maybe quite possible.

I would recommend you find three crew members that can vary your total boat/crew weight for three different wind conditions. Once you get used to the boat you can graduate towards the lighter crew weight.

I went from a H16 to a SolCAt 18 and then to a 1973 Tornado [US498] in three years. When I took my T out for its maiden sail I had a crew that weighed 105lbs and I weighed 170lbs. The winds were blowing the typical 10-20 with strong gusts. The second gust blew the T up so high that the lower rudder came out of the water. We were both leaning over the high hull so far when the boat came down we hit the water with our backs. This happened twice more before I could get to shore. I found a buddy and added an extra crew weight of 165lbs and went back out. We [3 crew] still had a hard time holding it down in the gusts but could have managed without the 105lb crew that day if single trapped [back then it was single trap and no spins]. The T weighed 279lbs.

Some may ask why the concern about capsizing the T. BAck then T masts had internal halyards and the masts weren't sealed. So when you capsized most likely tou turtled and broke every foam batten in the main. When I sold that boat I had three sets of battens [$365.00/set in the 1970s was more than some used cats bring today]. It would take a power boat to right the boat sometimes.

Even supertankers add ballast for stability; why shouldn't we???

fair winds,
thom

Jerry

As in a lot of things in life its all about the balance, if you take a Formula 18 boat for example.

These weigh 180 kgs, if you reduce that weight to 120 kgs and leave everything the same you will have a faster boat, but one that is less stable, if you then take the lighter boat and make it wider it can become just as stable and forgiving, but still faster.

Also you can bring the mast height and sail area down untill the boat becomes just as stable and forgiving as it was before, and the speed will also be about the same as the original.

The analogy with the a cat and the hobie 18 is not a good one since, the a is not only lighter, but narrower, faster, and has a mast about the same height, also you have two people to hold the hobie down and only one on the A. There are too many other factors that are different which also effect the stability as well as the weight.

Most boats that perform to a similar degree and are of similar widths will have similar amounts of stabilty.

Take the F16 for example, it is lighter than the f18, but as it has much smaller sails it ends up at about the same speed, also because of those smaller sails it ends up being about as stable and forgiving.

Also bear in mind that the width of a boat has a direct bearing on its speed (upwind and reaching anyway).

So rather than worrying about weight, you need to look at the equation of righting moment/heeling moment. As a guide you can take healing moment as 1/2mast height * mainsail area + 1/3/jib height * jib area. Then righting moment is boat width * 1/2 hull weight + (boat width +3) * sailor weight. (sailor weight here is for every sailor on a trapeze, if they are not trapezing remove the 3, also I'm assuming that boat width is measured in feet.

Uffa Fox, a very well known and respected yacht designer once said 'weight is only any use in steamrollers' and he's right.

I got the impression that Jerry was looking for a more simplistic response as to what is better for a novice sailor. If you want the more forgiving of two boats the same length, the Hobie 18 or the A-Class, it is a no-brainer.

The bottom line is that, as a woman, I would feel completely comfortable singlehanding a Hobie 18, main only, with my grandchildren aboard; but I would never take my grandchildren out sailing on an A-Class.

I also would not recommend the bigger, more powerful 20-footers for a novice sailor. Too easy to get out of control and into trouble.

We need something in the 16-18-foot range that is stable and forgiving. Not much out there in the "new boat" market for newbie sailors except for the Hobie Getaway.

Am I wrong?

Two other factors to consider are ruggedness and ease of
righting in a learner boat. No easy answer here, as in general the lighter the boat the easier it is to right, and
also in general, the heavier it is the more rugged it is.

Perhaps the best results are reached with a smaller boat.
I remember the Prindle 16 was both easy to right and tough.
As was the old Prindle 18. And lets not forget the Hobie 16.


The Hobie 18 is a battle ship, but can be tough to right.
The A class is very fragile.

Mary, Thom, John and Mark - thanks for the feedback.

I fully agree that rig proportions (as well as crew weight) factor into the equation, and that how forgiving a cat is depends on much more than boat weight, but it seems that weight is still a valid simplified way to look at overall stability since manufacturers tend to size the rig roughly proportionately to weight unless the boat is targeted at some extreme group (ie, Jav 2 may have a slightly bigger rig than the boat weight would oridinarily merit but this boat is targeted to the most highly performance oriented group). Also, it does seem to be some peoples experience that heavier boats are easier to handle in rough conditions.

John, I found your comments on heeling moment vs righting moment useful but I wonder if things aren't actually more complex than this depending on conditions. I would expect these to apply best when one looked at boat characteristics in steadier winds with flatter water; but in higly gusty conditions with big waves it's easy to imagine proportionately powered lighter boats becoming more difficult to handle, particularly for a non-expert sailor. I'm thinking that heeling and righting moments behave differently in steady state vs non steady state conditions.

Let's compare, for example, singlehanding an N17R or F18 (cat rigged) vs a F16. Aside: why do I want to compare N17R and F18 cat rigged? 1) see the recent thread about sailing TheMightyHobie18 solo and catrigged, 2)when I compared specs on the N17R vs the Nacra F18 I was surprised at how close they are:

Cat Length Beam Weight Mast Main Jib Spi
N 17R 17'5" 8'2.5" 335 lbs 30'4" 170 sf 37 sf 17 sm
N F18 18'1" 8'6" 385 lbs 29'9" 183 sf 37 sf 19 sm
Difference 8" 3.5" 50 lbs (7") 13 sf 0 sf 2 sm

(note: using smaller jib/spi option for F18 and subtracting about 10 lbs from ISAF I17N but not adding anything for jib or spi).

For example, taking F16 and F18: The F16 boat is lighter and has a smaller rig to give it similar overall performance. I would think that in gusty 20 kt winds and large waves the lower mass of the F16 would be effected more than the F18 by non steady state forces (gusts/waves): during gusts it would accelerate faster if well skippered or heel more if poorly skippered; when exposed to large waves it would be deviated or stopped more easily if poorly skippered than a heavier boat. I am NOT suggesting that F16 doesn't handle rough conditions as well as an F18 or that one boat is BETTER than the other!! Only that it may take a little more skill to handle the F16 in these conditions than a heavier F18. Note that if this is true, while this would make heavier boats easier for less experienced skippers/crew, it might also make them less fun and less a test of skill for experienced skippers/crew.

So, in summary, I'm asking if in demanding wind/wave conditions heavier cats such as N17R or F18 are easier to control and more forgiving than lighter cats such as F16. I'm also asking if a singlehanded F18 cat rigged would be roughly similar to an N17R as far as being stable and forgiving in rough conditions given their surprising similar specs (ie, is a F18 cat rigged as easy to sail as an TheMightyHobie18 cat rigged).

Experience and comments?

Jerry

Lighter is more forgiving..

Jerry,
While I agree, in general, with your technical conclusions, I disagree with your subjective conclusions.

The "fun" in racing is beating the other sailors in a fair race, (or so I have been told).
The true "skill" in racing is being able to make a given boat perform up to its maximum around a course.
There is no moral victory if you are on an over-powered, over-complicated boat and barely survive the race and get beat(handicap) by a well sailed H-16.

History has shown that most people don't like complicated boats.
The market is causing the complicated boats to become simpler; one-line spin launch and snuff, self-tacking jibs.

If you want to know what the rock stars like to race, it is all over the web.
Look how many F18, A Class, etc. champions are also H-16 Champions.

The skill is in pulling the lines just right and pointing the boat in the right direction and it is just as critical on all cats.

Well said Sam.

Two Things. Two of my opinions.
I don't much care how stable etc a cat is, if it is easy to right. Unstable and unrightable is zero fun, however fast. Easy to right, fast and unstable is considered a hoot.(Think of windsurfing, H16 in a blow...)
If I think about racing, with portsmouth, I often wound up against the same people. The boats changed, we got better at sailing, sometimes they had crew, sometimes not, but I still wound up racing against the same faces, seldom the same boat setup or weight, which makes me think that the whole business of class rules is a bit silly. I want to be able to fiddle with the boat, try and make up for my weight, and not give a damn about rules on my leisure time, handle the boat with ease, find a face to beat,have enough faces show up to make it a race,and social, and be cheap. So this 14 thing sounds good with unlimited sail area.
What do other regular Joes think?

Sam,

Thanks for your reply.

You said:
>> While I agree, in general, with your technical conclusions, I disagree with your subjective conclusions. The "fun" in racing is beating the other sailors in a fair race, (or so I have been told). The true "skill" in racing is being able to make a given boat perform up to its maximum around a course. There is no moral victory if you are on an over-powered, over-complicated boat and barely survive the race and get beat(handicap) by a well sailed H-16.

I think you may have read more into my comments than I intended when I wrote the post. I certainly didn't intend to define what is fun about cat sailing or racing. Of course this is a highly personal and subjective thing. In fact, I didn't even specifically focus my comments on racing. I was simply trying to get poeple's sailing experience comparing lighter vs heavier cats specifically as it relates to ease of maintaining control in difficult conditions for someone still on a learning curve with cats. My reference to "fun" was an echo of what I've heard many proponents of lighter designs state. So as far as my post was concered, I wasn't aware that I had arrived at any "subjective conclusions".

You said:
>> History has shown that most people don't like complicated boats. The market is causing the complicated boats to become simpler; one-line spin launch and snuff, self-tacking jibs.

I'm not sure what prompted you to bring this up - you're reading more into my post than I intended. I didn't mention complicated boats in my post, only lighter vs heavier ones. Granted, the examples I used for lighter and heavier boats are modern designs, but that is because I am interested in buying a new boat. In fact, there are far more complicated boats around than the boats I mentioned so I'm really not sure where you were going with this. As an aside, and not to be argumentative, it's actually not clear to me that history shows that most people don't like complicated boats. Maybe it depends on what you consider complicated. If you consider complicated boats to be current production boats from the major vendors selling production F16's, F18's, and various one-designs in the 16-18' range than I would have to respectfully disagree with you here. What makes these boats complicated? The fact that they have a spinnaker? Seems like many people are adding spis to previously simple boats including H16's. Many people do like these boats and they do seem to be selling well. Notice, however, that I'm NOT saying that many people don't also like more simple boats. It's a matter of personal preference. There's room for them all. Personally I think they're all great.

And finally you said:
>> If you want to know what the rock stars like to race, it is all over the web. Look how many F18, A Class, etc. champions are also H-16 Champions. The skill is in pulling the lines just right and pointing the boat in the right direction and it is just as critical on all cats.

Actually in my post I didn't ask what the rockstars like to race. I also think it's great that so many fine sailors started on a H16 - good boat. But what does that have to do with my post or my questions? Also, "pulling the lines just right" and "pointing the boat in the right direction" sounds like good general advice, but kind of misses the point of the original post.

Jerry

Mary

Your not wrong, the A would be more of a handfull, but is it because it is lighter, or is it because it has a proportionately more powerfull rig, or because it is narrower, or is it a combination of all three, I suggest that a Marstrom M18, which is a much wider A cat would be easier to sail with your grandchildren whilst still being half the weight. Also if you made a mistake and both boats were on their sides, which would be the most forgiving then, I suspect the heavy hobie wouldn't give you a second chance.

Jerry, I see where your going, the inertia of the heavy boat will carry you through waves when mistakes are made, but in general, the lighter boats need slimmer hulls, lower freeboards, and less resistance to those waves.

The biggest problem that someone learning a new boat in breeze will have is taming the rig, if two boats have the same ratio of healing moment to righting moment they will behave almost identically in gusts, but its just plain easier when you are trying to stay on the side, steer straight and looking where your going to dump the small main and then pull it in again than the bigger one.

Well, John, if I am taking small children out on a boat, I am not concerned at all about how easy the boat is to right, because if it is just me and small children, I am not going to be able to right it no matter what it is -- I'm going to be too busy taking care of the children floating around in the water or worrying about them getting trapped under the boat if it turtles. I want a boat that I can be confident is not going to capsize in the first place. Maybe that's why a lot of sailors with small children prefer a monohull with a keel, or maybe even a Lightning or a Flying Scot, etc.

Actually, I already have a safe catamaran for taking my grandchildren sailing. It's the Hobie Wave (a small, heavy, and underpowered A-Class cat).

Mary

Again your quite right, the wave is the boat for this task, but I would say that of the three reasons you justify it, small, heavy and underpowered, the two that really count are small and underpowered, and of these the most important is underpowered.

To get back to the original question, I can still think of no benefit to having a heavy boat, but if someone was convinced, there is nothing to stop them strapping a load of lead onto a light boat to make it heavy while they are learning, then taking it off when they want to. You can't take the weight off an already heavy boat.

Hi Jerry, just my thoughts, after having sailed both types, ie light & heavy cats :
Lighter is safer, with more stability. I`ll justify this as follows :

Most designers want a certain level of performance when designing a beach-cat. Relative performance is one of those things, ie Prindle would never have sold a single P16 if it`s performance was nowhere near that of the H16, it`s main rival at the time. So heavy boats are generally designed with more sail area than lighter boats. They have the same Power-to-weight ratio as lighter boats, but tend to become overpowered in heavy breeze.
If you were comparing two boats 16ft long, identical hull shape etc, one weighed 100kg with 16sqm sail area, the other weighed 150kg with 24sqm sail area. Assuming identical crew weights, you`d find the following :
- Boat 1 (light) would handle stronger winds than boat 2 (less sail area : crew weight ratio).
- Boat 1 would accelerate quickly in gusts (lower inertia), meaning that less of the force of the gust would be prone to capsizing the boat. Boat 2 (heavy) would resist acceleration, and the initial force of the gust would want to push the boat over before pushing it forward.
- Boat 1 would sit higher in the water, since 1kg of boat will displace 1liter of water, so boat 2 will have to displace 50liters of water more than boat 1 before reaching it`s displacement. This allows boat 1 to appear to have more bouyancy, in fact they have the same bouyancy, but boat 1 has a lower dispacement, meaning it will ride higher over chop & slam the beams less often.
- Boat 1 will be easier to right, less sail area = lighter mast needed to support it. To me, this is the most important factor. If I can`t right a boat, I won`t take it sailing. Ever. (Here I must disagree strongly with Mary - if you can`t right the boat by yourself when sailing with young children, I`d insist you stay ashore. Choose a boat you CAN self-right. If it`s a laser, then rather sail that than a Hobie 18. You WILL capsize one day or another.)

Yes, a lighter boat will be more responsive than a heavy one, but this makes it no less safe for beginners. just start off in lighter winds and build up gradually as your confidence improves.

And remember, this is only my OPINION.

Cheers
Steve

John, Mary, and Steve,

Thanks for the good input. You guys all raise some excellent points. Just to be clear, I don't have the answers (just the questions) - that's why I'm asking for your input! (and I do appreciate the responses)

Steve, in your post you said:
>> If you were comparing two boats 16ft long, identical hull shape etc, one weighed 100kg with 16sqm sail area, the other weighed 150kg with 24sqm sail area. Assuming identical crew weights, you`d find the following :
- Boat 1 (light) would handle stronger winds than boat 2 (less sail area : crew weight ratio).
- Boat 1 would accelerate quickly in gusts (lower inertia), meaning that less of the force of the gust would be prone to capsizing the boat. Boat 2 (heavy) would resist acceleration, and the initial force of the gust would want to push the boat over before pushing it forward.

It sounds like there could be some merit to this but let me play devil's advocate for a minute.

I'm not sure that sail area:crew weight ratio is any more meaningful than sail area:boat weight ratio. If the two boats are proportionately powered, I would think the greater righting moment of the heavier boat should compensate for the larger sail area and associated heeling moment allowing the heavier boat to handle winds similarly to the lighter boat. It's also not clear to me that even though a boat has less inertia and can accelerate better that it's less likely to capsize; when the heeling moment exceeds the righting moment it will capsize even if it's accelerating at the time.

You also said:
>> Boat 1 would sit higher in the water, since 1kg of boat will displace 1liter of water, so boat 2 will have to displace 50liters of water more than boat 1 before reaching it`s displacement. This allows boat 1 to appear to have more bouyancy, in fact they have the same bouyancy, but boat 1 has a lower dispacement, meaning it will ride higher over chop & slam the beams less often.

Lighter boats may sit higher in the water and may appear to have more bouyancy but I would think that would depend a lot on hull shape. But if they do sit higher in the water, appear to have more bouyancy, and are lighter it still seems like they're going to be more effected by waves than heavier boats.

Regarding lighter boats being easier to right, no argument there!

Jerry

I'm enjoying these discussions and learning by the minute so thanks for all the input.

So, one more devil's advocate argument that lighter could be less forgiving:

In the calculations of righting moment the key variables as pointed out by John (thanks, John) are boat width, hull weight, crew weight, and crew position (ie, hiked or not).

Now, on a heavier boat, the percentage change in righting moment is mathematically less sensitive to both crew weight and crew position becuase these are a lower percent of the total weight. On a lighter boat, crew weight and crew postion becomes much more critical in determining righting moment so that correct and optimal placement of crew weight becomes much more important in keeping the pointy side up. I would think this is even more the case in gusts (non-steady state) than under steadier conditions. From John's formula, notice how much righting moment decreases on lighter boats vs heavier boats particularly when the crew weight moves from the trap to the rail and then even more if the crew weight moves in to the tramp. Less forgiving?

Finally, speaking of crew weight, it would also follow that when crew weight becomes a larger percent of total weight on lighter boats that fore/aft placement also has a greater impact on sailing characteristics than on heavier boats. For example, this argument would suggest that the need to correctly position weight aft to keep a bow from stuffing may be more critical/sesitive on lighter cats than heavier cats. Less forgiving?

Also, just to clarify, I really like the idea of light boats! I'm just trying to understand what I would be in for if I go that route!

Thoughts?

Jerry

I suspect you still have a momemtum issue in big breeze.

light boat with crew will be stopped by large waves...
so you loose your attached flow on your sails and cannot respond quickly enough with the sheet to keep the boat going.

A heavier boat with same crew will have more momentum and a greater chance to maintain some speed and keep flow attached.

Robbie Daniels who race a Tcat and raced a prototype M20 for some time reported this behavior. He wasn't sure if developments in sailing technique could compensate in those conditions for the loss of mass.

Hi Jerry,
Let me clarify my post a little, and give you an insight as to where I get my ideas from : I don`t do the matehmatical approach (hell, I can`t even spell it !). Practical experience is where it comes from. I`m in the position where I`ve been sailing Mosquito 16ft cats since 1984. During that time the boats have gone from being 150 kg fibreglass boats, down to the new boats which are epoxy/foam or plywood, and weigh between 95-105kg. Let`s average that at 100kg. They both have the same rigs. Some of the old boats still exist, and still race. That`s why I stated that if you took 2 boats of IDENTICAL hull shape etc, as that`s where my experience is. What I did is this : I sailed an old boat at our Nationals 2 years ago, before upgrading to a new boat. I then test-sailed one of the new boats the same day in the same conditions, 18-20 knots, gusting 22-25. With the same rig, same crew weight, same crew experience etc, these are my findings :
Old boat tends to want to pitchpole more in gusts downwind - I attribute this to higher inertia, while the lighter boat "squirts" forward, bows hardly changing attitude, maybe due to quicker acceleration combined with higher "bouyancy". Now I KNOW that if we had a rig 50% bigger we would have had a lot of righting practice. This is not based on any formulas, just common sense.
Upwind the heavy boat would just want to lean over in gusts, with high inertia resisting accelaration, so you`d have to ease mainsheet in every gust, and sheet back in after the gust. Very tiring & not much fun after 4 races. The lighter boat again had very little heeling tendency, again "squirting" forward with acceleration, no mainsheet easing & pulling back in was necessary, just head up a few degrees in the gust to depower, and acually go FASTER ! This means that the lighter boat would gain height and speed in every gust, while the heavy boat would stand up on it`s side, slow down & then have to regain it`s momentum after pulling mainsheet back in, only to find the next gust approaching. Result : light boat gets to windward mark 2 minutes before heavy boat, and the crew have WORKED a lot less. An interesting point : the heavy boats were almost equal in speed upwind to the lighter boats in CONSTANT wind, only in gusty conditions did the lighter boat pull away. I know you`re not concerned with racing results right now, but at some time you will be. Also, you do less work to stay upright on the lighter boat with a smaller sailplan than on a heavy boat with a big engine.(unless you consider controlling the power with a gentle movement of the tiller as hard work.) Taller mast = higher pitching moment, heavier platform = more inertia ie resistance to acceleration. Combine the two & you have a pitchpole machine in the conditions I describe. No maths, just time on the water.
I specifically compared identical boats with only the weight differing, since that, I believe, would answer your question best.
I could have compared the Mosquito to the H16, theyr`e both 16ft long, one weighs a lot more than the other & has 25% more sail area, but they have different hull designs, platform widths etc, and so the comparison means nothing. (I`ve sailed both, they`re both great, so no, I`m not a Hobie-hater.) I`ve also sailed Dart 18, with an 8m mast she has a tendency to have the skipper hanging over the back beam downwind, hoping against all probability that she won`t dig in. (In 25knots plus, that is.)
In my opinion, and modern cat designers will disagree with me, lighter boat with lower aspect ratio sailplan is the best all-rounder. In light wind you won`t have the ultra-efficient sailplan of the A-cat, but in the heavy stuff I like to keep the power where I can see it. After all, it`s seldom in light wind that you feel completely out of control.
And on the issue of crew weight & boat weight : Crew weight is stuff you can use to your advantage, where at least half of your boat weight is always in the wrong place. Just learn where your crew weight belongs in certain conditions, and learn to do the weather rail shuffle (get back ! get back !)

Cheers
Steve