Scheal Keel

Bardo · #1 (**permalink**) 08-14-2007

The Tartan 33 that I am looking at has the Scheal (sp?) keel, which ostensibly allows the draft to remain shallow while providing the right ballast and weight ratios for good overall performance. Anyone have feedback on this design feature? It also has an exposed lead keel, which strikes me (pun intended) as a good thing should you run aground. Thoughts?

PBzeer · #2 (**permalink**) 08-14-2007

To my mind, it's not just the keel, but the overall underbody that you have to consider. My boat has a Scheel keel, which to me is another word for a modified fin. Longer than it is deep. My boat points well, goes well in reverse, and easily sails to her PHRF. I've been out in some decent blows, and the boat has always felt stable, while only having 4'6" draft.

I'm sure there are others who can give you a better technical overview, but for myself, I'm happy with the arrangement on my boat.

TejasSailer · #3 (**permalink**) 08-14-2007

Bardo,

On the Scheel Keel, the following article might be helpful (posted recently to a PSC thread).

http://www.ventureyachts.com/ph40shoalkeel.html

BarryL · #4 (**permalink**) 08-14-2007

Hello,

If you are interested in T33's you should visit this site:

http://www.tartanowners.org/t33.phtml

I was interested in the T 33 so I did a fair amount of research on them.

Barry

Bardo · #5 (**permalink**) 08-14-2007

Barry,
What led you to an O'Day rather than the tartan?

Bardo · #6 (**permalink**) 08-14-2007

Teja,
Great link! That lays it out perfectly, and eases my mind on the last detail of my boat search (HaHaHa). Okay, one of the last details. I think I'm sold on the T33. Now I just have to find the right one! Thanks for your help.

morganmike · #7 (**permalink**) 08-14-2007

While described correctly in the article, the flow streamlines in illustrations A and B are incorrect. Flow does indeed try to move from the high (actually ambient) pressure side to the low pressure side, but it does so by creating a wing tip vortex, a circular flow pattern that is high-drag inducing. What the Scheel keel does is the same thing as wing-tip vortice surfaces which are now routinely installed on airplane wings: it makes the vortice BIGGER, (have a larger diameter) than without it, thereby reducing the overall circulation and drag. That's the key distinction, that the Scheel keel does not eliminate the vortice, as shown in the article, it makes it larger. Illustration E is incorrect, it should look more like Illustration D with a larger (and thus less drag inducing) vortex.

You can't stop flow from high to low pressure, you can only shape it to avoid some of the unpleasant side effects.

morganmike · #8 (**permalink**) 08-14-2007

P.S. If you don't believe me, (since I'm just a guy with a degree in Fluid Mechanics and ten years experience in the field (but no Rep points)) then just ask Giuletta, he can confirm the flow principles, I'm sure.

Bardo · #9 (**permalink**) 08-14-2007

Morganmike,
Why would I not believe you? As an aviator, I am trained to believe anything that you hydro/aerodynamics geeks tell me. It is all PFM to me. Green is good, red is bad.

BarryL · #10 (**permalink**) 08-14-2007

Quote:

Originally Posted by Bardo

Barry,
What led you to an O'Day rather than the tartan?

Hello,

I was looking for a 33 to 36' boat. I had a number of boats on my list, including Tartan 33, Catalina 34 and 36, O'day 35, Hunter 33.5 (90's or newer), C&C 33 (late 80's), etc.

One thing I didn't like about the Tartan was the early interior layout with the pilot berth and very small settee. Otherwise the boats are very nice, but pricey.

The big thing about the O'day was the rear swim / boarding platform. My boat is on a mooring and I row out in a dink. The rear platform makes getting on / off the boat very easy. My kids and I also like to swim off the boat.

The real reason I bought the O'day is because I found a nice one for a good price. I just missed getting a Tartan 33R. That would have been a great boat.

Good luck,
Barry