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Old 09-12-2022, 07:07   #1
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Sailboat conversion to motor cruiser

Hello to the Power Boats forum.

I’m planning to convert a sailboat to a motor cruiser. Are there any threads here (I couldn’t find any), books, blogs, blogs, websites, etc., that I can study?
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Old 09-12-2022, 08:10   #2
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Re: Sailboat conversion to motor cruiser

look up steve dashews FPB boats. they are power cruisers based on sailboat hull form for motoring effiency. you will need stabilizers of some kind.

i got a rhodes 19 for free years back, no rig no rudder no board, just a hull... i cut out the centerboard trunk and glassed it up, cut the little cabin top off and laid down a solid floor, stuck a 15hp on a braket on the back and a huge bimini top and i had a comfortable cruiser that would get into skinny water and still took it fishing offshore when the weather was nice... anything can be done...
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Old 09-12-2022, 08:18   #3
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Re: Sailboat conversion to motor cruiser

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Originally Posted by rsementi View Post
Hello to the Power Boats forum.



I’m planning to convert a sailboat to a motor cruiser. Are there any threads here (I couldn’t find any), books, blogs, blogs, websites, etc., that I can study?


Dashews motors boats are multi million dollars vessels so it may not translate well !!

Really you need the services of a NA or buy a motor sailer that might be suitable
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Old 09-12-2022, 08:18   #4
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Re: Sailboat conversion to motor cruiser

Are you saying to look up that steve dashews FPB boats here on this site? Or does he have his own site? I’ll google it too.
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Old 09-12-2022, 11:34   #5
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Re: Sailboat conversion to motor cruiser

FWIW: when we were dismasted, thus becoming a vessel like you describe, the motion at sea was horrible... fast and jerky and dangerous to all aboard. The mass of the mast adds greatly to the polar moment of the boat, reducing the accelerations due to pitching and rolling.

You may well need to do something to compensate for the loss.

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Old 09-12-2022, 15:51   #6
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Re: Sailboat conversion to motor cruiser

This is do able but rarely successfully the basic hull design for a sailing vsl is verry different from a purely motor vsl ,that being said ,we have altered many older style motor vsls into comfortable motor sailers ,shallow draft ,large props ,smallish rigs ,means going to windward under sail alone is near impossible ,but the steadying influence of a sail often adds to the comfort factor overall , but it’s all about compromise .⛵️⚓️
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Old 09-12-2022, 16:19   #7
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You could probably do it with a hard chined wood or steel Hull with the fin keel cut off and a long shallow keel welded in place..
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Old 10-12-2022, 05:19   #8
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Re: Sailboat conversion to motor cruiser

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I’m planning to convert a sailboat to a motor cruiser.

Why? What's your end goal, intended use, etc.?

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Old 10-12-2022, 05:43   #9
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Re: Sailboat conversion to motor cruiser

What are your intentions? If you are going from waterway to waterway in near coastal and protected waters and your boat will be a house boat mostly? Then you should be good, as much as we like to aggrandize our journeys and the conditions, our vessels mostly sit in idle, if you do not know how to sail learn or sell it and buy a power boat there’s lots of then around and it’s point and shoot, once you fill up. If you modify a vessel you most likely will make it significantly harder to sell or insure.
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Old 10-12-2022, 07:21   #10
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Re: Sailboat conversion to motor cruiser

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FWIW: when we were dismasted, thus becoming a vessel like you describe, the motion at sea was horrible... fast and jerky and dangerous to all aboard. The mass of the mast adds greatly to the polar moment of the boat, reducing the accelerations due to pitching and rolling.

You may well need to do something to compensate for the loss.

Jim
Yep, typical sailboat hulls are notorious for having horrible motion even in modest sea conditions without the mast up.

Basically mass further from the center of rolling has the greatest impact on reducing rolling. Even though the mast and rigging don't way a lot, they are very far from the center of rolling, so they have a big impact. Remove them, and the boat becomes a wobbly mess.

To get an idea, take a broomstick and roll it 180deg then back 180deg between your finger tips. Now try to spin it 180deg and back just as fast.

You might look at an older sail catamran. Unlike a monohull, they are inherently stable due to hull form.
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Old 10-12-2022, 08:24   #11
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Re: Sailboat conversion to motor cruiser

an old school sailor .. Bruce vanSant .. who wrote the book "Passages South" .. converted a Schucker to trawler.


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Old 12-12-2022, 05:25   #12
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Re: Sailboat conversion to motor cruiser

A couple of reply’s speak of boats bobbing and rolling without a mast.

All motion is dependent on a couple of things, size and weight of a vessel in relation to sea state plays a major factor. Small boats will be influenced more than large sailboats. Heavy displacement sailboats will move less than light displacement, full keel will move less than no keel.
The OP has not stated the intended use, power or sail, longer, heavier, wider, will have less movement proportional to the sea state.

What’s your intended use? Off shore or dock squatting? Close to the equator or upper latitudes? What size? More data will give you more accurate responses
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Old 12-12-2022, 05:47   #13
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Re: Sailboat conversion to motor cruiser

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A couple of reply’s speak of boats bobbing and rolling without a mast.

All motion is dependent on a couple of things, size and weight of a vessel in relation to sea state plays a major factor. Small boats will be influenced more than large sailboats. Heavy displacement sailboats will move less than light displacement, full keel will move less than no keel.
The OP has not stated the intended use, power or sail, longer, heavier, wider, will have less movement proportional to the sea state.

What’s your intended use? Off shore or dock squatting? Close to the equator or upper latitudes? What size? More data will give you more accurate responses
While it's true that a 50ft without mast will likely be more stable than a 25ft without mast...the 50ft without mast will typically be much worse than the same 50ft WITH mast up.

Also, if just living dockside never moving, you can get away with a lot but even in seemingly benign bodies of water can be problematic. Example: you wouldn't think motoring on a river would be bad but we've had water over the cabin top on the Mississippi due to an 8ft vertical face wake from a big tow going up river. Also, there are sections of the ICW that should be millpond calm but a steady stream of idiots throwing big wakes on sections a couple hundred feet wide make them anything but.

So, yes, you can motor with the mast down but I wouldn't count on a good ride without some form of stabilization to counter the loss of the mast. Honestly, much better to get a power boat hull (with small motor) and go at sailboat speeds)...aka, get a trawler and go slow.
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Old 12-12-2022, 06:03   #14
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Re: Sailboat conversion to motor cruiser

It probably would be better to get/build a full displacement power boat. A boat designed to not have a mast and has the efficiency of a sailboat hull.

A designer that popped up from a google search on displacement power boats -
https://www.tadroberts.ca/services/s.../displacement/
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Old 12-12-2022, 06:20   #15
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Re: Sailboat conversion to motor cruiser

I am guessing you want to do the loop.

Ex Sailor on the loop now in a trawler. You can follow us on the loop here https://www.youtube.com/@theadventuresofyorksieandme

We've encountered a few sailboats with the mast permanently removed, a few pontoon boats with homemade houseboats on top that looked like they wouldn't survive a 15 knot wind, a guy on a jet ski, and power boats in such bad shape I wouldn't take them out of the slip on a calm day.

These folks made it across the Great Lakes and down the Mississippi. I know this as we encountered them repeatedly along the way.

So the answer is yes, you can just take out the mast, plug the hole with bondo or whatever, and head out - and survive - but do you want to?

Why not keep it a sailboat, and strap the mast on deck when you need bridge clearance, or have the mast shipped forward?
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