my new keel foil or no foil

[stone_love]

Made my new keel using the 1/2 plate with 3/8 plates welded to it making it about 6 ft long and 1.25" thick.


After additional lead additions I've gained a few lbs over original design but thinner.


Should I just give the front a rounded nose and tail a point and call her good or give her a foil shape with some wood and foam

[THE CUSCUS]

All depends on how well you want your boat to sail. Just making the factory keel smooth and making the edges uniform made a difference. http://www.macgregorsailors.com/modt/in ... ?view=1484

[stone_love]

I don't want a race boat but I want her to point as well as possible and head into the wind as well as possible

[THE CUSCUS]

I have read of others who used flat plates, and they stated their pointing ability was less than acceptable. Think of it as your underwater "wing". Would you want you sails flat? You took the time to build what you have so far, why not go the extra few yards and finish it? easier now that its fresh and clean. 1-1/4" thick is alittle thin, and will bang around in the trunk. I believe youd want it to be more like 1-1/2", but I would measure the ID of your trunk to be sure. The keel trunk is wider at the bottom than it is at the top.

[stone_love]

the top portion is identical to the way it came factory, i'm re using parts of the top fiberglass/epoxy casing that go up into the centerboard/surround the pivot bolt

My boat is badged w/21 and should be a 1964 model, she doesn't even have a keel lock bolt or a hole for one.

For the most part she's identacle to the V/21's but the keel is a little different.

I've got some wood and foam so as long as i'm not slammed with customers today i'll work on putting a foil on the lower 2-3 ft of the keel

[THE CUSCUS]

Oh, didn't realize your boat was a V21 and that old, so alot of what I said isn't valid for your application.

[Russ]

I have read of others who used flat plates, and they stated their pointing ability was less than acceptable. Think of it as your underwater "wing". Would you want you sails flat? You took the time to build what you have so far, why not go the extra few yards and finish it?

I would agree with this. Seems like you've done a lot of work on it. At the very least, reducing the drag will be a plus.

Get crazy and put fins on it.
http://www.macgregorsailors.com/forum/v ... =8&t=16387

[stone_love]

hmm....no fancy bulb shape....just a large fin fitted from an outboard to the bottom of my keel....

I think i like that idea!

[finding41]

Make a foil shape. It will make a big difference. Here is a link to some foil guru web site.... I don't know... but I used it to make the 0012 foil for my rudder.
http://www.worldofkrauss.com/
or google air foil generator.
NOTE; you want it to be the same on each side. If not it will point really well one way. Not so much the other way.

[finding41]

Read this. http://www.macgregorsailors.com/forum/v ... =8&t=20170
See how easy it is.

[Catigale]

Need lift to point....otherwise it's just ballast..

[stone_love]

I shaped it pretty close to that of a wing spoiler I took off a car a few years back.


Pointed pretty well on my first sail...put in at a ramp upwind from our cove for convience of easy sail my first time out. Then noticed water coming in hull and had to shoot up wind back to ramp. It was a very narrow channel especially with the lake down nearly 20 ft.

My first time ever sailing and she tacked easily and quickly in 5-10 MPH wind.

I may have guessed close. Upwind she was fast enough to hum the cable

[Catigale]

When you hit A440 you've got it right.,...

[jtis1]

I have an 85 Mac 22 with the keel out in my garage. I just scraped the barnacles and rust and reprimed/painted it. If I want to smooth off the numerous rough spots what do I use-Bondo?

[stone_love]

I have an 85 Mac 22 with the keel out in my garage. I just scraped the barnacles and rust and reprimed/painted it. If I want to smooth off the numerous rough spots what do I use-Bondo?

unfortunately bondo is crap!!!

use epoxy resin.

aero-marine makes great epoxy, so does us epoxies. Both are reasonably priced, US epoxies is cheaper.

Get the 3-1 mixtuer in US epoxies plus their thickener.

Add thickener to the mix and spread it over your entire preped (cleaned, sanded down, cleaned again, then cleaned again with acetone) to get a perfectly smooth surface. Depending on how good you are with a spreader will determine how much or little sanding you are going to do.

Will need to sit at least 24hrs in 70deg weather before she's ready to sand.


Then paint over epoxy resin with your favorite bottom coat.