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Longer rudder

Jun 3, 2016
10
Catalina 18 BRANCHED OAK LAKE
If I installed a longer rudder would that help prevent my Catalina 18 from rounding up so quickly?
 
Nov 8, 2010
10,586
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Yes, but unless the boat design has a known tendency to round up, you would probably be best off focusing on why and under what conditions you are developing so much weather helm. Mast rake is on quick place to look. Also, most boats have built-in weather helm and will round up at some point. You might want to get a 2nd opinion on what is going on.
 
Jul 20, 2018
13
Catalina Capri 18 Everett, WA
Slacker,
Please keep us updated on your efforts. I find that my Catalina 18 rounds up too quickly as well. I have a devil of a time balancing the sails enough to head below for a quick trip to the cooler.
It is possible it is designed that way.
It is possible my mast is raked too much. I will update any changes I make as well.
Cheers,
Nate
 
Jun 3, 2016
10
Catalina 18 BRANCHED OAK LAKE
A tiller extension is a necessity but I’m hoping a sailing swami will shed some light on this . I know I need to be more aware of sail position but in the best of situations if the boom Vang is tight you almost can’t react in time to a gust of wind
 
Aug 1, 2011
3,492
Catalina 270 Wabamun - on the orange ball
You should probably expect that hull to be capable of significant changes in direction on a moment's notice. Based on your second post, I'd offer that you get out and sail it a whole bunch before you start entertaining changing mechanical things. Check the rig against what the design docs suggest, mast rake and the like, and get some pictures of the setup and share them. This almost sounds like it's maybe more of an operational issue than a design one.
 
Jun 3, 2016
10
Catalina 18 BRANCHED OAK LAKE
I took a picture of the C 18 mast which shows about an inch rake and I also included a picture of an S 2 in a slip next to mine which has considerable more rake in the mast. Mine was set up with the help of the Catalina dealer . I've owned the boat about 12 years
 

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Sep 6, 2019
11
Catalina 18 Mass
I am currently in the market for a C18. This is the first I have heard that they have a tendency to "round up" into the wind?
 
Last edited:
Apr 16, 2017
630
Federation NCC-1701 Riverside
Under what circumstances does the boat round up. I like this boat too and would like to know more. When motoring, at hull speed do you have good control? What kind of keel do you have?

This to me looks like a hull form issue and less to do with sail trim.

Ive attached a picture of the catalina 18 with a First 18. They look similar, but the first has a longer rudder, and a centerboard. The sail plan looks similar, the hull shape is similar. Woulds be helpful to know if anyone on the board had been on both boats or atleast the First 18.

Both boats have fat round hulls. When those heel, the shape pushing through the water goes from a long oval to more egg shape, basically, the forces countering rotation around the keel is less. like standing in a pool, with arms out paddling water it hard to turn, bring arms in and irs easier to turn.

One other issue when heeled (with pressure on sails) is the lenght of that keel on the C18. The flow coming off that is turbulent, more so if stalling sideways, the rudder may not have clean flow to work with. With a higher aspect centerboard or keel there is more lift at speed, less sideways slipping, less turbulence from the keel and hull form.
 

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Jun 3, 2016
10
Catalina 18 BRANCHED OAK LAKE
That makes sense . The hull shape has to make a difference .This is a wing keel . I must say that at the point it rounds up the wind is usually around 18 to 22. I've been paying more attention to sail trim and that makes a big difference . I might be making too big an issue . I was out a couple of days ago and was fine but I talked to sailor with a Hunter 23 and he had reefed the main but I was fine .
 
Apr 16, 2017
630
Federation NCC-1701 Riverside
The boat is sold as a gunk holer trailer sailer camper for relaxed sailing. Keep it flat with reduced sail and lighter sail pressure and enjoy it as is.

Id be concerned about any rudder that extends past the keel.
 
Apr 16, 2017
630
Federation NCC-1701 Riverside
While looking over the specs I see my Hunter 170 shape is very similar to the Catalina 18, just scaled down slightly. Here's a Sketchup of the C18 in both the level sail and the 30 degree heel. Each hull is placed on a plane to simulate the interaction with the water. The views on squares are the wireframe that is under the "water", an outline can be made where the plane intersects the wireframe.

I think I could have angled the nose of the heeled over version a little more to match online pictures and a probably could have sunk the transom slightly, but overall should look pretty close. Most pictures show very little transom under water. The lofting lines were estimated from the top view, side view, transom and pictures online.

The heeled over version has an extreme asymmetrical shape that could contribute to difficult handling, especially as the rudder is also at a 30 degree angle.

If the model should be adjusted I'll make the changes. I look at the drawings and wonder if this boat can actually sail 30 degrees heeled without water going above the rub rail.
 

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Last edited:
Jun 3, 2016
10
Catalina 18 BRANCHED OAK LAKE
This boat can't get the rail in the water without rounding up first