Monohull verses Multihull powersailers / motorsailers

[sabahcat]

Motorsailer
http://www.endeavourcats.com/

Fast cruiser
http://www.schionningdesigns.com.au/www/welcome.cfm

[TeddyDiver]

Trawlers aren't motorsailers, anyway not with the standards I've used to.
Schionning on the other hand has a quite nice range of sailing cats, from what's more a racer like to proper ocean cruisers and motorsailers and almost everything btw.

[sabahcat]

Originally Posted by TeddyDiver

Trawlers aren't motorsailers, anyway not with the standards I've used to.
Schionning on the other hand has a quite nice range of sailing cats, from what's more a racer like to proper ocean cruisers and motorsailers and almost everything btw.

Click on sail for endeavourcat, they are motorsailers

First pic endevour motorsaler
2nd pic Pescott whitehaven cruising cat

I wouldnt consider any schionning to be a motor sailer, they can happily sail at windspeed up to about 15 knots+

[Manie B]

This thread has had some very interesting points
and i am rather glad that i read it
i firmly believe that a proper sailing cat still makes for a very efficient motor cat even without mast or sails
same motion and very light on fuel at 10 knots

here are the underbridge shapes from HELL

i didn't know whether i should laugh or cry - so i did both

farkit i cant believe it

go to schionning - that is proper design

[Fanie]

If you're 20 you need one 20 year old.

If you're 40 you need 2 twenty year olds

if you're 60 you should go for 3 twenty year olds.

It's not for what you think.
It's so they can do stuff you're too old to do

[TeddyDiver]

Originally Posted by Manie B

i firmly believe that a proper sailing cat still makes for a very efficient motor cat even without mast or sails
same motion and very light on fuel at 10 knots

Couldn't agree more
A motorsailer can do it's hull speed with sails or motoring.
A trawler, cat or mono, with some rags hanging on top doesn't make it a motorsailer.

[brian eiland]

Seems as though this subject thread has gone dormant...too bad as there was a lot of interesting material here.

Per one of the words in the title of this thread 'Powersailers' I thought I would bring up this 40 powersailer from Thailand.
http://tinyurl.com/catamaran-power-sailing-HK40

It utilizes that aft-mast arrangement I've touted for a long time. Seems the Hong Kong owner is quite happy with it. There are several more being built. In fact I've been told the second one is being launched today, and that I will receive some new photos soon.

Here's the first one

[sabahcat]

Originally Posted by brian eiland

Seems as though this subject thread has gone dormant...too bad as there was a lot of interesting material here.

Per one of the words in the title of this thread 'Powersailers' I thought I would bring up this 40 powersailer from Thailand.
http://tinyurl.com/catamaran-power-sailing-HK40

It utilizes that aft-mast arrangement I've touted for a long time. Seems the Hong Kong owner is quite happy with it. There are several more being built. In fact I've been told the second one is being launched today, and that I will receive some new photos soon.

Here's the first one

One has to ask how much diesel-miles you can buy for the cost of the mast, sails, furlers, chainplates etc.

[brian eiland]

But one also has to ask about the unlimited range that the sailing option offers. Are there that many 'strickly powerboats' you are willing to, or capabile of crossing oceans with??

[sabahcat]

Originally Posted by brian eiland

But one also has to ask about the unlimited range that the sailing option offers. Are there that many 'strickly powerboats' you are willing to, or capabile of crossing oceans with??

Do you really think that particular vessel is one?
I think it more designed to cruise around the land of cheap diesel and not much wind.
That being the case, my comment stands.

[DennisRB]

What a great post. Yeah I know its 5 years old but you nailed the concept and reality of motor sailing.

Originally Posted by Bob Leask

A LIVEABOARD CRUISER FOR THE REAL WORLD

I'm working on a design concept that might seem a bit eccentric, but here's how the idea germinated:

I just finished a circumnavigation in a 37' traditional double ender of my own design, but to say that I sailed around the world is to use the word "sailed" a bit loosely. She's a heavy boat, around 30,000 lbs, and when the wind is 15 knots or better she'll make good time, my best 24 hour mileage was a little over 150 and in good sailing conditions I averaged about 125. But when I did a review of my logbook and estimated how many days I had such conditions, I came up with a rough estimate of about 25%. And that's optimistic. I did more or less standard trade wind westabout passages at the right times and latitudes and found that the pilot charts can be very misleading. The pilot charts give average wind strength and direction compiled from observations of deep sea vessels over long periods of time, but the figure they give for probability of calm is way off, from a cruising sailors point of view. If the observer saw any ripple at all on the water, the report would have been Beaufort 1, but anything less than Beaufort 4 for all practical purposes is flat calm, if you're trying to sail in a heavy displacement boat. All full time liveaboard/cruising boats less than 45 feet overall should be considered heavy displacement. If they aren't before you moved aboard, they will be by the time you've moved everything you own onto them, including fuel, water, food, stores, spare parts, tools, books, souvenirs etc. etc.

Having voyaged over 30,000 miles I have come to the conclusion that idyllic trade wind sailing with steady winds of 15 to 25 knots for 24 hours is a dream, or a myth made up by writers of cruising stories. I've never experienced a single day like that, anywhere.

However I found out early on, in the calms that prevail on the west coast of the mid-latitude Americas, that low speed motoring is a very good way to make passages in flat calms. Motorsailing is by far the easiest and safest way to cope with highly variable conditions, when the wind is constantly varying from near calm to 25 knots and back again cyclically, which is common. In my experience trade winds were always variable to some extent.

The days when I had my best passages were not the most pleasant. To make an average speed of near 6 knots meant that some of the time I was overcanvassed and overdriven, which can be exhausting and uncomfortable. It's hard to relax when the boat is heeling and rolling heavily, and at any moment you might have to take in a reef if the wind increases any more. To get into passagemaking and seamanship is too big a subject so I'll leave that now, but just summarize by saying that relying entirely on sail to cross oceans is not as easy as many might think, or hope, or want to believe.

Early in my voyage I found out that my boat would motor at four knots and burn 1 liter of diesel per hour in flat water. That means 96 miles in 24 hours which is quite an acceptable rate for ocean passagemaking and when you can buy fuel in places where it's cheaper, such as latin america or southeast asia, the cost per mile is very reasonable. When I was in Indonesia the price of diesel fuel was less than 15 cents US per liter. Of course I can throttle up and go faster, but fuel consumption goes up exponentially. At my top speed of 7 knots the consumption is about 3.5/hour, roughly 1 US gallon.

Here is some very simple math: to go around the world (about 30,000 miles) divided by 4 knots would have cost me a total fuel consumption of 7,500 liters. At the current high prices today of about 60 cents US per liter the voyage would have cost me a total of $4,500 dollars in fuel. Add to that a guesstimate of $1500 for oil and filters etc. and we have a grand total of $6,000. Think you can set up a sailing rig for that price? And you can spend plenty on all the bells and whistles to gain more sailing efficiency, and add to that the cost of larger battery banks and solar and wind charging systems, to cope with electrical requirements when under pure sail for long periods.

And another hidden cost of offshore sailing: the heavy wear and tear on sails and rigging while trying to sail in very light and variable conditions. One day of flogging your sails in light air and a swell running, quite a normal experience at sea, probably shortens their life more than weeks of hard sailing. When you have lots of wind the sails stay full and are under a constant load, but they aren't wearing much, and the same goes for your standing rigging. When you hear about dismastings at sea they almost always happen in light and variable conditions. When you do the simple math, you can't avoid the conclusion that from a purely economic point of view, it's unlikely that sail propulsion can ever come close to the cost effectiveness of an efficient diesel. Flogging that expensive sailing gear to bits to go very slowly makes no sense at all. The miles I sailed cost me a lot more than the miles I motored, probably by a factor of 3 to 1. By the time I got home all my sails were totally worn out. My engine is still going strong.

Here's a broadside at the sailing purists: those who haven't lived among the offshore cruising community might be amazed at how often they are sailing "dark ships", with no navigation lights at all, to conserve battery power. A totally idiotic practice but it's shocking how often it's done.

The sailing purists have already clicked out, those still interested in where I'm going are now thinking that I haven't considered engine breakdowns and rebuilds. I have a simple answer for that, it's a single word: Sabb. After the thousands of hours I've put on my Sabb 30 horse engine from Norway it's running exactly the same as it did when I got it, secondhand. I'm pretty sure that it'll still be running long after I wear out. It may outlast my boat, too. Low speed diesels like the Sabb are designed to run efficiently at low rpms and you can idle them for long periods without damage, unlike modern high speed engines. The bearing surfaces are so large that at such low speeds the wear on them is practically nil. I'm willing to bet that my Sabb would do another circumnavigation without major trouble, just the way it is.

The high efficiency is for several reasons: One is that I don't have a heat exchanger. I used a Walters keel cooler and dry exhaust which saves much of the energy wasted by running in effect two cooling systems. The low rpm engine design is another, as is the controllable pitch two blade propeller which comes standard with the Sabb 2J. It has a large diameter and is always optimally pitched. And I have no doubt the efficiency could be improved. But it definitely beats any other sailing auxiliary diesel I've heard of so far, by a wide margin.

Another observation of mine was how much fuel cruising sailors actually do use. When I admit that I motored or motorsailed approximately 50% of the way around the world, I'm simply using the records of my log book. What I am quite sure of is that I used less fuel than the average cruising "sailor". Almost every other cruiser I met in harbour after a long passage had used nearly all their fuel, and most of them carried more than I did, my own fuel capacity being only 210 liters. I would say that on average, those claiming to be "sailors" were using more fuel on passage than I was. The reason for that is that the average sailing auxiliary yacht built these days is abysmally inefficient for motoring. Too small propellers, badly designed propeller apertures, high rpm engines that are inefficient at low speeds, and wasteful heat exchanger/wet exhaust systems are to blame. All of those things are done for the sake of incremental improvements in sailing performance. Fuel efficiency is simply not part of the equation in the design of modern crusing boats.

Motorsailing offshore is by far the most pleasant way to make passage, most of the time. With the engine barely above idle and a moderate amount of sail set, there is a synergy created by the apparent wind which generates more forward thrust than either one alone, with the bonus that you don't have to set large areas of canvas, which will have to come down in a hurry if the wind increases. The boat rides better, makes a better average speed and the batteries are always full. The beneft of using a much smaller sailplan can only be appreciated by someone who's been caught offguard in a squall with too much sail up. "Adventures" like that might be fun for weekend sailors and short coastal passagemakers, but on a long ocean passage they're something to avoid, even if it means a slower passage.

Now that I've made my case for the motorsailing offshore cruiser, I'll describe my design which is a work in progress. For a lot of reasons I've chosen a catamaran as the best overall type for long range cruising and living aboard. My main reasons are shallow draft, beachability, visibility from the bridge deck salon and ample deck space. Even the slowest cruising multihulls generally beat monohulls on passage times. However I view that as a bonus, not a primary design objective. With my slow boat I spent about a week in harbour for every day I spent at sea. When you're wandering around the world on a boat, speed is simply not an important issue. Comfort, liveablility, economy and versatility are the things that matter most to a liveaboard/cruiser. If you can have those qualities and go faster too, that's great.

And now I'm finally coming to the point. After much time spent browsing the offerings of boatbuilders and designers around the world, I've found nothing, zero, zipola about achieving maximum fuel efficiency per mile, with mono or multihull boats. Where fuel consumption graphs can be found, most of them start at five or six knots. It seems that there is not a single professional boat designer working today who is interested in designing boats to be used in the real world, the way offshore cruisers actually use them. The main design objectives are speed speed and more speed, and anything less than 3 gallons an hour is touted as "economical".

There are a lot of designs I like, in particular at: http://www.runningtideyachts.com/motorsailing/, but in this case information is lacking as to actual fuel consumption rate, displacement and payload, and fuel capacity. Can such a motorsailing cat carry enough fuel to make a 2000 mile passage? Is the fuel efficiency only relative, compared with other boats at the same speed? In the real world when you might have to motor on one engine at a minimal speed to stretch your fuel out over a long passage, does the efficiency still apply, or is it better/worse than the average cruising monohull?

In terms of optimal fuel economy per mile for monohulls and multihulls of the same displacement, monohulls have a theoretical advantage. Going strictly by experience because so little data seems to be available on the subject, I believe the most economical speed for a yacht is at around 50% of hull speed where wave making resistance is not important and skin friction will be the major factor, but optimal speed will depend on whether or not the propulsion system is designed to operate at a low power output efficiently, and that for me is one of the most crucial things for a good offshore cruiser, but does not seem to be considered at all in the modern world of boat design. Why not? A little more simple math will tell you that even if you don't mind the cost, it just isn't possible to carry enough fuel for long motorsailing passages in a boat of 40 feet or less, especially a multihull, if your consumption is over a liter or two per hour. You simply can't carry enough fuel to go the distance.

Which brings me finall to the concept that I've settled on: a catamaran with three engines. Two will be outboard motors mounted on the sterns of each hull. The third will be a small, low speed diesel, preferably air cooled, on the centerline housed in a pod. I expect to pay a penalty in wetted surface higher than a monohull of the same displacement, offset by the fact that a multihull can be a bigger boat with less displacement, which I hope should work out approximately equal. The outboard motors will be lighter weight and cheaper to install, and will provide higher power when high speed is wanted, albeit at a much higher fuel consumption. The high redundancy factor in this design will add to safety, with enough power to get out of bad situations like dragging anchor in a confined area. Outboard motors won't have the service life of inboard diesels but will probably not be used very often, almost never offshore. They're easily serviced or replaced, and it would be possible to carry spares onboard. New ones are available anywhere.

My most basic question now is what would be the best combination of engine and drive? The belt drive system described on http://www.runningtideyachts.com/motorsailing/ makes a lot of sense, it would virtually eliminate mechanical loss. The best option of all might be a direct drive or longtail system, if the problems of installation on the centerline are solvable. There are some very good gensets on the market that might be easily adaptable to a direct drive with a chain or belt reduction, and voila, you've got an economical auxiliary and a genset all in one, that will work fine while you're beached, too. Yet another option would be installing a genset wherever it pleases you, and using an electric motor for propulsion. That's also a nifty idea, because a fixed magnet electric motor will also serve as a very good water generator while you're sailing. Lots of electric power at all times while underway, eliminating the need for elaborate and expensive solar/wind power systems. And no limit to propeller diameter with either system. Either way it could be made to easily retract out of the water and with the outboards retracted up as well, no propeller drag while sailing at high speeds.

Has anybody here been thinking along the same lines, or know of anybody who's done anything similar, or have any ideas? I know the idea of a multihull that isn't designed to be a seagoing hot rod is a little radical, but after weighing the pros and cons of every other idea I've thought of, it seems the best one. A monohull designed for low speed economy might be the absolute best motorsailer for long passages, but could not have as shallow a draft as a cat. Shallow draft and beachability are my main design criteria, a little time in the third world with a boat that requires a travelift to haul out will teach you why.

Comments?

[brian eiland]

Another interesting observation from the log books of an ocean cruising sailor:

"Mike, a number of years ago I went through the log book of my trip through the S. Pacific to New Zealand and back. In 174 days at sea over 5 years the ketch Saga spent about 10 days actually on the wind. While there were certainly times when it would be good to go up wind better, taking a boat to sea that is hard to sail just to optimize those 10 days would be stupid.

During the same cruise I spent about 34 days with the chute up, where I didn't use the mizzen because it didn't do anything but slow me down. I was sailing about 160 to 170 degrees apparent wind.

The conclusion I have to come to for a cruising boat is that one should optimize reaching so long as the boat isn't un-safe. Lee shores are still dangerous."

Beau
This came as a response to this quote:

...However the lift to drag ratio upwind will always favor the minimum number of sails, currently that is the sloop for larger boats. Once you get out of the racing arena it's a different ballgame anyway and what appear huge differences in a racer become insignificant on a passagemaker.

BTW, this posting came from a really good subject thread entitled
Why a Yawl or Ketch instead of a sloop

[DennisRB]

Mike, a number of years ago I went through the log book of my trip through the S. Pacific to New Zealand and back. In 174 days at sea over 5 years the ketch Saga spent about 10 days actually on the wind. While there were certainly times when it would be good to go up wind better, taking a boat to sea that is hard to sail just to optimize those 10 days would be stupid.

This is only true for a retired cruiser who waits all year. Cruisers who only have holidays when they can get them need to sail upwind. I just sailed from Adelaide to Newcastle via Bass Strait and we were on the wind more than half the time. Of course if I had unlimited time I would have waited for more favorable winds.

[brian eiland]

Originally Posted by DennisRB

This is only true for a retired cruiser who waits all year.

I'm not sure of his wait time in this case, but he has spent a lot of time at sea:

As to ('this retired cruiser's') experience sailing:
- 47 years at sea
- 15 years driving schooners professionally
- 105 days at sea last year, 32 so far this year, thousands of days under sail over the last four decades on every sort of sailing craft
- longest trip in the last few years a 5 year trip around the Pacific
- sailed everything from a banks dory to a 158' schooner
- built everything from a pram to a 50' yawl
- built in wood, steel, fiberglass, the only thing I passed on was cement
- raced extensively

Cruisers who only have holidays when they can get them need to sail upwind. I just sailed from Adelaide to Newcastle via Bass Strait and we were on the wind more than half the time. Of course if I had unlimited time I would have waited for more favorable winds.

I can appreciate that you had a cruise that developed into a lot of windward work, but a great majority of the accounts I read don't seem to support lots of windward work.

[DennisRB]

That is an impressive history and BeauVrolyk certainly is a very experienced seaman who deserves respect. However the time spent to windward was not as a portion of that entire history. It was of a portion of a 174 days at sea over 5 years on the ketch Saga. 5 years being long enough to pick favorable winds when going through the S. Pacific to New Zealand and back. Cruisers who might get a month or 2 off will probably want to end up in the same place they started (home port), and they will be very lucky indeed if the wind always blows the way they are going over such a small rigid time frame. I cant wait until I have unlimited time so I almost never have to sail upwind. But until then its mostly up to the weather.

Also, have you considered that many cruisers who might say they never sail upwind do so because their yachts are simply so terrible at it that they pretty much don't even have that option? The Roberts Spray that my sailing buddy owned made its way to Australia from South Africa, Asia and the Pacific Islands. Now I can guarantee they didn't do any windward work as this poorly performing yacht simply could not do it. We promptly got rid of the yacht as it was entirely useless for any trip we tried to do on it due to not having the time to wait for perfect winds. When you get 2 weeks off you cant wait for the winds to change. The boat we used on the Adelaide to Newcastle trip could sail to windward OK and because of that we made it as far as we did. The Spray would still be in Adelaide for 8 months until the trades change.