Keel Fairing

[richardschmidt2759]

does anybody know if i't worth the work to fair the aft end of a mainship 1 keel?

 

[Nomad Willy]

Pics and boat speed?

 

[Scary]

Probably not

I's not a racing boat, I doubt if you will reduce any drag. It could improve bottom shots however, for the forum.

 

[DavidM]

Fairing may not do any good. I faired the deadwood behind the keel on my Mainship Pilot 34. I couldn't tell any difference. And by Mainship I I presume you mean the original 34 sedan. That is at best a 12kt boat with the Perkins 165, so I wouldn't expect much improvement there either.

Here are before and after pics of my keel:

 

[Mule]

Go to the Mainship yahoo forum, there are extensive conversations. In the archives there are pix and how to. One guy claims he picked up 300 rpm as memory serves. More impt to me is upsizing the too far forward, undersized rudder. Mine is sold to be funded this week.

 

[C lectric]

I don't know about your boat but I've seen a couple done including one Seabird 37' sailboat owned by a fellow I know.
It was not to pick up any speed. It was to reduce noise. The trailing edge of the keel was blunt and close and the eddies and swirls, when they hit the prop, caused a lot of noise.

He was a shipwright and had experience with doing other boats for much the same reason.
He told me it made a noticeable difference. I cannot verify it because I didn't hear the before and after.

On a powerboat , even a slow one, it might help noise reduction. Just a question of how much and is it worthwhile. That I cannot answer.

 

[Nomad Willy]

C lectric,
Not putting your comments down one bit but we have a 6 knot Willard and she has a very squared off keel termination and don't have a vibration problem at all.

One or two Willard owners have done the mod but I have no knowledge about improvement or not. I thought about it but my concerns about efficiency were in another life. Not enough time either. You could probably spend your time or money better elsewhere.

But I may be wrong.

 

[jleonard]

Fairing the keel is without doubt worth the effort. I did tha job on my ex Mainship 1. Just from that alone I gained 250 rpm at WOT and you can do the math what that means thru the entire rpm range. I was able to add 2 inches of pitch and still spin up to proper rpm and then some.
It is a very simple project that takes maybe 6 or 8 hours worth of labor. I made my fairing bullet shaped.

Mule, that was me and I thought the rudder was fine but I guess that's a matter of opinion.

By the way you can witness and perhaps prove to yourself as I did how the fairing will help. I did this one driveway at home during a rainstorm. While the water was running downhill I took a 2x10 and used it to dam up the water just the the flat end keel on the Mainship. I was amazed how much the water was displaced as it went around the board. It really upset the water flow. I was convinced a fairing would help.

 

[Mule]

Fairing the keel is without doubt worth the effort. I did tha job on my ex Mainship 1. Just from that alone I gained 250 rpm at WOT and you can do the math what that means thru the entire rpm range. I was able to add 2 inches of pitch and still spin up to proper rpm and then some.
It is a very simple project that takes maybe 6 or 8 hours worth of labor. I made my fairing bullet shaped.

Mule, that was me and I thought the rudder was fine but I guess that's a matter of opinion.

By the way you can witness and perhaps prove to yourself as I did how the fairing will help. I did this one driveway at home during a rainstorm. While the water was running downhill I took a 2x10 and used it to dam up the water just the the flat end keel on the Mainship. I was amazed how much the water was displaced as it went around the board. It really upset the water flow. I was convinced a fairing would help.

Ok, I was looking at doing your mod next time out, but she sold first. The rudder issue came to a head when I had a 5 knot ebb in the Fort Pierce inlet take the boat away from me twice. I was giving her all she had, 9.5 knots, normal 14.5, and lost her 2x. Had to hard to hard to get her pointed. I was ready the second time, still could not stop her. That is when I determined, along with the following sea issue the rudder was not right.

After that underwear tearing incident I determined it might be wise to keep ebb and flow in mind when shooting the inlet. Lesson learned. I went from 250 hp Cummins @ 7 ton to 135hp@ 13 ton so tidal movement will be a priority hence forth.

 

[richardschmidt2759]

Thanks guys! great response to a new guy! glad I joined this group! I will most likely do this job while up for winter. I live in jersey so cold weather will be here soon, need a new project! THANKS,AGAIN RICH S . P.S I will let you know how it worked out in the spring.

 

[jleonard]

This is a picture of what I did the only one I can find. I made the base blocks from 2 pieces of pressure treated 4x4, epoxied them to the hull, then faired them with a disk grinder, then 3 layers of 1 1/2 ounce mat and polyester resin, gelcoat when finished.

 

[Mule]

Just to be clear.....before pix....

 

[jleonard]

Just to be clear.....before pix....

I don't have a before pic but the keel was flat as it is where the stern tube bolts on. All I did was ADD the fairing blocks above and below the stern tube.