Sail hull trawler conversion questions

[Jackdaw]

Actually, and I just learned this, the keel is why it rolls. By lowering the center of gravity and lateral resistance, with a keel, there is a resistance to movement well below the surface, while the bouyant hull moves according to the wave action. This means there is an exaggerated roll, like lengthening the string on a pendulum that keeps the same swing and period. A tall mast acts as a dampener and slows down the period so the swing isn't as exaggerated.

Since much of the ballast in the keel is designed to stabilize the boat under sail, removing much of the keel could work, especially when adding a larger engine low in the hull. However, the hull form with rounded bilges may make for an uncomfortable ride, especially if the boat is lighter over all, resulting in more overhang coming out of the water. A lot of pitching as well as rolling.

-Will (Dragonfly)

Umm... I think you need to rethink this.

Lowering the CG will always reduce roll, with a corresponding shortening of the period. Its not a pendulum; a pendulum pivots freely while a keel is fixed to its hull.

Now on a sailboat without a mast, very long righting arm creates a period is so short that most people find it uncomfortable. As noted, the mast (and even better sails) provide a dampener to that.

 

[PaulK]

Here's a good motorsailer: 63′ William Hand Motorsailer

Definitely not just a pilothouse sailboat.

 

[LloydB]

In reading your original post it looks like you may really want a catamaran. So far as I know all boats roll but I believe the catamaran generally rolls the least. I have seen some pretty catamarans although I personally prefer the looks of sloops. If you find one in about the same shape as the Jenks 45 hull then you should get to where you want to be with about half as much money same amount of work because you would still have 2 smaller engines to install but no conversions or changes to the boat hulls.

 

[JohnRichard]

In reading your original post it looks like you may really want a catamaran. So far as I know all boats roll but I believe the catamaran generally rolls the least. I have seen some pretty catamarans although I personally prefer the looks of sloops. If you find one in about the same shape as the Jenks 45 hull then you should get to where you want to be with about half as much money same amount of work because you would still have 2 smaller engines to install but no conversions or changes to the boat hulls.

That's a very interesting thought. I only mentioned roll because of some other reading about a sail hull without the mast being overly rolley. Its not something I was actively trying to mitigate, just asking questions.

I've given some thoughts to Cats, and will see what is available, perhaps that is the right choice?

 

[shemandr]

William Hand is some eye candy! Does it come with a boatyard full of craftsmen?

 

[dLj]

You started this thread asking some questions regarding a specific boat. Perhaps you want to start a new thread addressing more specifically what you think you may like to do and the constraints around which you need to work - like budget...

A guy I know says - hey you can do just about anything if you throw enough buckets of $100 dollar bills at it....

dj

 

[MrDrew]

I have a Morgan 45' built in 68. The full keel boat has an issue I can't seem to master. Reversing out of the slip with the constant wind the boat literally will want to 90 degrees right out of the slip and face stern to the runway headed out of the Marina which has everyone running with their boathooks. The boat does not steer in reverse . I thought it was pilot error and then I let some one try it with their knowledge of full keel boats ( No Luck ) Going forward not a problem, in fact the boat handles great sailing and powering in forward positions. Lately I've been hearing of the articulating props which seem to have a greater power in reverse. Does any body have any views on these propellers for full keel boats.? Perkins 4108 50 HP. ratio 2/1. Thanks

 

[Will Gilmore]

The Morgan 45 has a rather short waterline. It also looks like her mast is stepped quite a good distance ahead of her center of lateral resistance. I don't know as much as many on here, but I suspect the prevailing winds and your prop are working together to walk the stern into the wind and blow the bow down wind. I don't know if increasing power in reverse will work. I'd look for a prop with slimmer blades to try reducing prop walk.

Never fear, I'm confident others with real experience with this will chime in soon.

-Will