Convert trawler to motorsailer?

I agree w RTF ...
Perhaps you really want a sailboat.
But your boat bsaically is a sailboat .. I think.
I think your sail rig should be sized according to the percentage of time you'll be under sail. Close to most of the time would warrent full sail rig.

If I were to do this it would be the other way around. I would rarely use the sails (if at all) except as stabilizers.

I was trying to size it to be a "sail assist" instead of a true motorsailer. So basically, I will still always be running the engine but have the sails up when I want a boost or stability. Almost exactly like Mark does with his Coot, but maybe with a little more boost from the sails due to more area and a more "slippery" hull?

After a lengthy search as requested, but doubt it is of little help.



I particularly like this view. Sail power not enough to pull out dock cleats.

Mark, what's that mast height?

About 30 or 31 feet above the waterline. The mast is attached to a tabernacle, mounted on a one-inch-thick fiberglass roof adjacent to a steel bulkhead.

Larry M said:

Cardude: If you're going to add a shorter mast and smaller sails, why not go all the way and install as close as you can to the full height mast and full sails? You'll have a larger group of potential buyers when you sell, a more efficient motor sailor and who knows, you might like sailing?

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Larry,

Good question. Not sure I have a logical answer.

I was trying to size it to be a "sail assist" instead of a true motorsailer. So basically, I will still always be running the engine but have the sails up when I want a boost or stability. Almost exactly like Mark does with his Coot, but maybe with a little more boost from the sails due to more area and a more "slippery" hull?

Maybe I'm a little afraid of the stress of a full size rig? I was also thinking that a smaller rig would be easier to handle single handed?

Like I said, no logical answer.

And hey, when I want to sell I can advertise it as a "sail assisted" trawler. Not many of those around so it could bring a premium! [emoji51]

Nomad Willy said:

...

If I were to do this it would be the other way around. I would rarely use the sails (if at all) except as stabilizers.

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Just using the mainsail, although smaller than than the jib, is less work.



Both sails, together, are more efficient.

Cardude,

My boat has a 200 square foot mainsail and 100 square foot jib. 300 sq ft total pushing 6 1/2 tons.

Your sail area per ton ratio would work out fairly similar with sail area you are considering. Perhaps its a bit less.
A rough rule of thumb is each 50 square feet of sail produce one horsepower in 15 knots of wind; so it would equate to another 7 1/2 horsepower.

With that much sail you are unlikely to run sails only unless you want a lazy quiet cruise at 3-4 knots. For stabilizing it is perfectly sized. Easy to handle in most conditions. It may still be worth to have one set of reefing points set up on it, as I think you have a fairly shallow keel like mine.

As far as motorsailing benefits, the gain in speed from the sails would depend on the speed under power. Normally I just reduce engine speed from 2000 to 1700 to maintain my normal cruising speed when I have the sails up.

AusCan said:

... Normally I just reduce engine speed from 2000 to 1700 to maintain my normal cruising speed when I have the sails up.

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Just wondering...couldn't you maintain the same engine speed, get there sooner, and save pretty much the same amount of fuel...or is the physics not quite that simplistic?

Would there be any advantage to building a ketch rig?

Pack Mule said:

Would there be any advantage to building a ketch rig?

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I can't answer that because I don't really understand the differences, but Just looking at my boat I don't know how one would mount the smaller mast. Things are in the way.

Don't forget, that your boat was not built for having excess force above the deck. You might require considerable weight at the keel or in your case the bilge to keep the boat from healing excessively. Many 40 foot sailboats have keels ranging from 5000 to 8000 pounds. of course, their sails are much larger than anything you would ever put on a boat.

Just food for thought.

Gordon

Gordon J said:

Don't forget, that your boat was not built for having excess force above the deck. You might require considerable weight at the keel or in your case the bilge to keep the boat from healing excessively. Many 40 foot sailboats have keels ranging from 5000 to 8000 pounds. of course, their sails are much larger than anything you would ever put on a boat.

Just food for thought.

Gordon

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It actually does have 5000 lbs of ballast in the keel, just 500 lbs less than the fully rigged out SP Cruiser according to the engineers at Island Packet, back when they were a going concern.

Not meaning to be out of line... but... Gee, if I were to want my power boat to actually become a full time sailing-ready boat... think I'd sell it and get a pilot house motor sailor... it would be already outfitted and equipped. Just sayen!

Art said:

Not meaning to be out of line... but... Gee, if I were to want my power boat to actually become a full time sailing-ready boat... think I'd sell it and get a pilot house motor sailor... it would be already outfitted and equipped. Just sayen!

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Not out of line. I understand that wanting to add sails to a boat seems like a stupid idea to most here on TF, especially since many came from sail boats. I'm not trying to turn it into a full time sail boat, but more of a sail assisted power boat like some of the Aussies on TF have.

Thing is, I've looked at motorsailers for sale and can't find any in the same price range as my boat that aren't older and junky or that match the amenities I have on my boat. The really nice, newer motorsailers that I like are seriously expensive.

My boat is nice and fairly new and updated and I like it, but just want to fiddle with some sails.

cardude01 said:

Not out of line. I understand that wanting to add sails to a boat seems like a stupid idea to most here on TF, especially since many came from sail boats. I'm not trying to turn it into a full time sail boat, but more of a sail assisted power boat like some of the Aussies on TF have.

Thing is, I've looked at motorsailers for sale and can't find any in the same price range as my boat that aren't older and junky or that match the amenities I have on my boat. The really nice, newer motorsailers that I like are seriously expensive.

My boat is nice and fairly new and updated and I like it, but just want to fiddle with some sails.

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Don't fret, cd. At one time I was musing plans for adding mast and sail onto our Tollycraft. After thinking clearly on it I decided to not pursue that agenda too far....

Art said:

Don't fret, cd. At one time I was musing plans for adding mast and sail onto our Tollycraft. After thinking clearly on it I decided to not pursue that agenda too far....

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Really! Have any drawings? That would have been an interesting project.

cardude01 said:

Not out of line. I understand that wanting to add sails to a boat seems like a stupid idea to most here on TF, especially since many came from sail boats. I'm not trying to turn it into a full time sail boat, but more of a sail assisted power boat like some of the Aussies on TF have.

Thing is, I've looked at motorsailers for sale and can't find any in the same price range as my boat that aren't older and junky or that match the amenities I have on my boat. The really nice, newer motorsailers that I like are seriously expensive.

My boat is nice and fairly new and updated and I like it, but just want to fiddle with some sails.

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I don't think it's a stupid idea at all. I do think you'd want to discuss this with a naval architect. Your boat was designed to carry sail, you just have to work out the details.

cardude01 said:

Really! Have any drawings? That would have been an interesting project.

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Years ago, Larry – avatar: healhustler – briefly discussed “sail things” with me for my boat. He may have photoshop on those thoughts?? I’ve no drawings… just what remains in my mind from thinking on it years previous. When I was beginning to think clearly on adding mast and sails as a limited propulsion source to our 21K lb. when loaded, 34’ tri cabin, twin screw, self-contained, low center of gravity, planning hull Tollycraft – fuel prices were nudging the $5 to $6 dollar per gallon. Since then, fuel costs have reduced so much that the sail add-on, for a boat such as mine, appears non-productive cost wise and use wise.

Following are old threads that have sail discussion. There are probably other threads that could be searched to find.

http://www.trawlerforum.com/forums/s3/why-we-have-trawler-not-sailboat-21392.html

http://www.trawlerforum.com/forums/s3/2013-boat-options-8166.html

Best Luck!!

Art

MurrayM said:

Just wondering...couldn't you maintain the same engine speed, get there sooner, and save pretty much the same amount of fuel...or is the physics not quite that simplistic?

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I could, but the gain in speed isn't much under these circumstances. At 2000 rpm I usually am at about 6 knots (about a knot under hull speed). The sails would only add about 0.1 or 0.2 knots in extra speed, but the reduction of 300 rpm gives me a 20% drop in fuel use and substantially less engine noise. That is usually my preferred option.

Art - I don't think a sail conversion project would ever recover costs from fuel savings, unless you are circumnavigating.

In my eye, fuel savings are a very small advantage of a motorsailer. By far, stabilisation in rough water is the biggest plus to me. Other motorsailer advantages like "get home propulsion" and "something to tinker with" are also a big plus.

When one approaches hull speed under power, a sail-assist rig will not add much. Works best when you're engine-powering below one-knot of hull speed. My one-knot-below hull speed RPM is 1800. If expecting any help from the sails, I apply only 1400-1600 RPM.

cardude`s boat resembles a motor sailer. I think it`s a great idea. Does the build include provision for supporting the mast on deck, or will there be a post extending to the keel? I fitted a compression post to a small sail boat when I was concerned about how well the deck was tolerating the load.
Can you get enough sail area so it can just be sailed? Maybe a spinnaker, that would be fun, even a "gennaker", a hybrid genoa/kite.

BruceK said:

cardude`s boat resembles a motor sailer. I think it`s a great idea. Does the build include provision for supporting the mast on deck, or will there be a post extending to the keel? I fitted a compression post to a small sail boat when I was concerned about how well the deck was tolerating the load.
Can you get enough sail area so it can just be sailed? Maybe a spinnaker, that would be fun, even a "gennaker", a hybrid genoa/kite.

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The sail version of this boat is keel stepped so that's what the rigger wants to do.

As far as getting enough sail on the boat so it sails without the engine, the sail plan with the 40' mast and just two sails won't be very speedy (maybe 3-4 knots if the sails produce 7-8 hp in 15 knots of wind) without the engine running at all, and like FF said the prop will cause some drag.

The spinnaker idea is interesting.

My engine makes about 8hp at about 1400rpm and burns about 1/2 gallon per hour doing that, so maybe a combo of 15 knots of wind and 1400rpm will get me about 6 knots. That's a 2400 mile range! I can make it to Hawaii now!
[emoji23]

Can I run this little Yanmar at only 1400 rpm for long periods of time? I'm just kidding about Hawaii, but maybe I will cross the Gulf of Mexico one day.

For you sailors/riggers/mathematicians out there, what is the reduced stress on a rig with 700 sq ft of sail (the factory size rig) vs 377? Is it linear or logarithmic?

cardude, I like the looks of the sailrig on your boat . It just looks right . Just think of all the extra shade you could hang off of those sticks when in the tropics . It would really increase your cooled off lounging area. Go for it man !

Pack Mule said:

cardude, I like the looks of the sailrig on your boat . It just looks right . Just think of all the extra shade you could hang off of those sticks when in the tropics . It would really increase your cooled off lounging area. Go for it man !

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That was another reason for doing it, as crazy as that sounds. I'm constantly looking for places to hang my hammock. Lol.

After two years of yacking about it, I'm finally doing it. Well I'm not-- Mack Sails in Stuart is doing the work.

A few pics. More pics coming this weekend after I go check it out in person.

Sailboats get to go out in Blue water because of their construction.

Adding a mast to a motor boat does not change the vessels scantlings.

A parasail is easiest to rig , but simply slowing down to SL.9 will give low fuel burn,at no cost.

Wow this is going to be interesting. Are you going with original sail plan that IP has for your boat ?

Yes this is the sail plan the Island Packet folks drew up back when they were still Island Packet. Basically the same as the SP Cruiser, but with a little shorter mast and smaller sail plan due to a little less ballast in my boat, and because I wanted a low stress setup that would last quite awhile and be easy to single hand.