50/50 or 100/100.

[Vega]

Originally Posted by Guillermo

I think your engine should allow you to deal (motoring alone) with gale force head winds in sheltered waters, not open seas with 4-5 m waves. Maybe that's too much and, with a fixed propeller you'd have to slow down rpm just not to overload the engine if you have to motor for a long time. So probably 150 HP for a 42' 10 ton boat is much more than needed.

When in a gale in open waters, if you have to motor, you'd probably will not try to go directly into the wind, but motorsail into it at an open angle with the proper set of sails. That's wiser and that's what motorsailers are good for.

Cheers.

I am not talking of motoring directly into the wind, but at a reasonably close angle. Remember I am talking about pure motorboats, and that when you will need the extra power (safety power) of your motor, it will not be in sheltered waters.
And if you can safely (but uncomfortably) motor home, that is right ahead in the wind, say at 15 miles, why should you turn around and motor more conformably to a 30 mile port that it is not your own?

A motor boat should have some advantages over a motorsailor, don’t you think?

Seriously, Guillermo, you could contribute a lot to this discussion. Can you see what is the power that fisherman have there in a boat like the one we are talking about? I don't mean trawlers, but the ones that need engine not to pull nets, only to move the boat.

Those are the guys with real experience in what kind of power a motorboat needs to maximize safety.

[FAST FRED]

If you do the math , the windage at 50K for most boats isnt that high, and the usual reserve of engine power most boats have will handle it.

The problem of besting 12 to 20 ft waves is more a matter of accepting a slower speed of advance. A VP prop would be a big help , as it would in the pure sail mode.
The biggest hassle with requiring extreme amounts of thrust is the size and cost of the large diameter prop required to do this effictivly.The deeper reduction gear costs about the same , although the $haft dia will be larger.

Of course this is a 1 time cost and the added efficency of a huge slow turning prop will lower fuel consumption while motoring or MS , might actually pay over the long term..

FAST FRED

[gonzo]

Sailboats have no motors. With a motor installed, it is either an auxiliary or a motorsailor. The boundary is rather subjective. The percentage for the sailing part assumes a high performance sailor without the drag of a propeller, underwater openings, shafts, etc. The motorboat assumes a performance motorboat that is at least semidisplacement.

[Vega]

Originally Posted by gonzo

Sailboats have no motors. With a motor installed, it is either an auxiliary or a motorsailor. .

It is rather funny to call to all high performance offshore racing sailboats "auxiliaries". That’s what they are, according to you.

[Guillermo]

Originally Posted by Vega

..Can you see what is the power that fisherman have there in a boat like the one we are talking about? I don't mean trawlers, but the ones that need engine not to pull nets, only to move the boat...

Good question. Unluckily fishing vessels owners nowadays (Well, yesterday, because nowadays they become to be worried with fuel costs) are (were) not really worried about fuel costs and they tend to overpower vessels, maximizing cargo, crew accomodation (this last not always) and fishing equipment, forgetting about hydrodynamics, fuel efficiency and the like . This trend has produced what I understand as cramped ugly vessels (but very efficient predators of the seas). Even today, with all the worrying, what they really ask for is not more efficent propulsion systems, but cheaper fuels
So it's better to go back in time and see what happened several decades ago, with boats like the 50' LOA Irish fishing boat I posted in the Trollers vs Trawlers discussion (Was that one?). She mounted an 88 HP, 750 rpm diesel engine, moving a 32" x 19" three bladed propeller. The boat moved at 9 knots at the designed waterline load condition. Displacement: 28.9 tonnes. Consume: 18.2 l/h.
Mmmm....I'm realizing I have a lot of info on old fishing boats from the world around, and maybe some day I will take the time to do some statistical work.
Cheers.

[gonzo]

That is the definition of auxiliary. I didn't make it up.

[Vega]

Originally Posted by Guillermo

Good question. Unluckily fishing vessels owners nowadays not really worried about fuel costs and they tend to overpower vessels, maximizing cargo, crew accomodation ...So it's better to go back in time and see what happened several decades ago, with boats like the 50' LOA Irish fishing boat I posted in the Trollers vs Trawlers discussion (Was that one?). She mounted an 88 HP, 750 rpm diesel engine, moving a 32" x 19" three bladed propeller. The boat moved at 9 knots at the designed waterline load condition. Displacement: 28.9 tonnes. Consume: 18.2 l/h.
.

Well I agree, but lets look at what they used to have 20 years ago and not at what they used when they did not have the choice to do otherwise.

That Irish boat looks like a boat built in the 50's or beginning of 60's. I bet that if they had the technology (small engines) and the money (economic situation) they would have put a more powerful motor in that boat.

Of course if you chose to have a look at the engines that the fishing boats of the same size carried in the 30's, you are going to find 35hp engines.

So let's not exaggerate and perhaps look at the motors that they used 20 years ago?

[Guillermo]

Originally Posted by Vega

..So let's not exaggerate and perhaps look at the motors that they used 20 years ago?

That's an idea, but there are other ways, as estimating power with some well known formulas used for fishing boats design.

Also we can do something even simpler:
The Irish boat (Disp = 28.9 ton; Lwl = 46' 8") is using 3 HP/ton, which was accepted as a nice power for sailing boats 30 years ago. For efficient motorsailers nowadays my opinion is that we should move around 5 HP/ton, bringing in the Irish case power to 144.5 HP. In my opinion sailing boats with HP/Disp < 3 should always be classified as 'Auxiliaries', as discussed before. Between 3 and 4 let's say there is the 'subjective' zone gonzo talks about.

My simple formula to estimate power (posted in 'Motorsailers' thread), HP = K * Lwl * (Lwl - 10), although out of range here (works more or less accurately only between 20'<Lwl<40'), using K=0.1 for a heavyweight like this Irish boat, gives a power of 171.14 HP, so almost 6 HP/ton, which is somewhat high. In my opinion efficient motorsailers should have a power between 4.5 < HP/Disp < 5.5. Let's say we can accept from 4 to 6, depending on appliances aboard, etc. In the last times there's has been even a tendency to overpower, clearly ultrapassing 6, with the showing up of semiplanning or even planning motorsailers (!)

(Note: I've analized 85 motorsailers, with Lwl between 24' to 60')

[safewalrus]

Whats in a definition? so sailboats with engines are either auxilaries or motorsailors eh! why not call ALL sailboats with engines 'motorsailors' or all motorboats with sails 'sailormotors'. Does a 'drifter' with a steadying sail make it a 'sailing' drifter (I don't think so)! Even today a lot of Danish boats operate like this! Or to be more obtuse, is the old HMS Warrior (1860 vintage) three masted sailing war ship with a single propellor and a big engine room/boiler room and a crew in excess of 600! classed as a 'motorsailor' - technically yes! 'Motorsailor is not really a sensible definition is it?

Unfortunately the numbers game played by some tends to confuse the majority! Also why go back 20 years (according to my reckoning thats not the 50's or 60's) are we looking at boats now or is this about history - and if it's about history lets get back to the correct use and definition of words as used then!

[gonzo]

The term motorsailor was a marketing ploy. The salespeople claim you could get the best of both world without any drawbacks. However, sailboat and powerboat are easy to define.

[FAST FRED]

"The term motorsailor was a marketing ploy.

Yet Herrishoff described his offshore fast cruiser , the Marco Polo , long befire Madison Ave created thew usual add blither.

For folks looking for fast passage times the Marco Polo should be the starting benchmark.

At 55ft she was designed to maintain 10K in offshore cruising using power with sails.

Today the engine would have more reliability and weigh 1/10 of the old iron monster and with backyard skills cored GRP hull construction the hull could weigh 1/4 of the origonal.

The pointy stern would have to go for better speeds and sea keeping , and of course the intereior and layout are archaic by todays standards .

But the M/P was a fine sea boat from folks that have had the pleasure of a ride.

A modern version of this concept would be a DELIGHT!

FAST FRED

[yipster]

100/100 say 80/80 is two boats indeed, look at Malcolm Tennants motorsailers and a dedicated retractable propulsion nowadays shouldnt be that difficult i figger

[Tad]

Marketing ploy? Madison Avenue?

Yacht Designers, like everyone else in business, have been forever inventing quasi-technical terms to delineate their work from that of others. I am lead to believe that the term Motorsailer was coined by some unknown yacht designer trying to feed his kids.

They were originally referred to as 50-50's, but this inferred less than great performance in either mode. This term was used by William Hand to describe his design , Nor'Easter, launched in 1927. The motorsailor term seems to have appeared in 28 or 29, as Hand's Bluebill of 28 and John G. Hanna's Centaur of 29 are both referred to (in various publications) as Motorsailers.

In the early 1930's Rudder magazine ran an article entitled "The Case for the Motorsailor". I was a collection of remarkes by five prominent designers of the time. The designers were, Gordon Munro, Bill Hand, Walter McInnis, Thomas Bowes, and John Hanna. In it Hanna states, "The motorsailor goes back to fisherman origin. Though reluctant to adopt the engine, once they did the fishermen were quick to increase to full power, and they saw they might as well cut down rigs to heavy weather size, as it did not pay to fool with sail at all in light weather.....William H. Hand was the first designer to produce motorsailors in sufficient numbers to establish a distinct yacht type."

Some designers totaly rejected the Motorsailor term. Philip Rhodes produced Tamaris in 1938 and insisted that she was not a motorsailor but a "Full-powered Sailer". Francis Herreshoff would not use the term, calling Marco Polo and her forbearers Ocean Cruisers or Auxiliary Ketches.

All the best, Tad

[Guillermo]

Very interesting post, Tad. Do you know how to get a copy of "The Case for the motorsailor" article?

"....Hanna states, "The motorsailor goes back to fisherman origin. Though reluctant to adopt the engine, once they did the fishermen were quick to increase to full power, and they saw they might as well cut down rigs to heavy weather size, as it did not pay to fool with sail at all in light weather....."

This confirms the origin of the motorsailer concept as a motor boat with auxiliary sails, bred in fishing boats. As a matter of fact it happens to be what the term evokes to most of the people.

Herreshoff and Rhodes reluctancy to use the term is well present still nowadays, as many boatbuilders/designers do not want their boats being subliminally labeled in people's minds as heavy, slow & bulky old fogeys.

But nowadays there are beautiful examples of 'Teenys' (Motorsailers with both figures in my labeling system in the 13-16 range), like the Noordkapper 40 or the Perry 45. Nothing to be ashame of.

[gonzo]

Fasr Fred: I don't think "any with backyard skills cored GRP hull construction the hull could weigh 1/4 of the origonal." Do you know the displacement as designed? Wood construction, by Herreshoff's rules is of moderate weight and great strength. I can't see how low quality sandwich construction can compete. Also, it wouldn't be a Herreshoff. He strongly emphazised that he would never allow one of his boats to be built out of "frozen snot"