Cape cod 17 catboat

[Rodbone]

I'm looking for my next project (about to sell a 74 Herreshoff Eagle I've worked on for two years) and am looking at a Cape Cod Shipbuilding 17 ft. Catboat. I was surprised to learn they actually have a fixed keel model in addition to the centerboard choice. I guess I have an affinity for Catboat like hulls as I went on a quest 20 years ago to find and buy a Legnos Mystic 30, and now the Eagle. Both could maybe be called Catboat wannabes!

Anyway although never having sailed a Catboat, I understand they have notorious weather helm, and the logic as to why makes sense. I've also read that the way to combat that is to not always sail with the centerboard all the way down. Evidently cranking it up just a bit can reduce helm and doesn't sacrifice much on pointing.Well I'm wondering if the weather helm also applies to the boat I'm looking at, and if so, since there is no centerboard. how do you handle it. Have any of you experienced sailing one of these?

 

[Brian S]

Reducing centerboard helps with weather helm in two ways. It reduces the amount of the foil, which reduces the lift to windward, thus reducing the rolling moment from under the boat, effectively depowering the boat. I have seen some impressive footage of a Laser with full daggerboard being overpowered and hiked aggressively, and a second Laser on the same course with a bit of dagger board up, sailing flat and comfortably with not so much hiking. Of course, the board shouldn't be raised so much that significant leeway is induced.

And secondly, on a centerboard which pivots down, lifting the board some also pivots the center of resistance aft with regards to the sail's center of effort, thus reducing the weather helm. It's kinda the opposite of raking the mast forward, which would be what you'd do while tuning a rig.

Also, I think that the reason a traditional-looking catboat has weather helm is because instead of using a higher aspect transom hung rudder, they use a low aspect transom hung "barn door" rudder. With that much rudder stretching aft of the pivot point, it will make for a very heavy helm feel. You can see the difference with a lifting rudder as you raise the blade. I've found a blade trailing aft just below the surface is almost un-steerable in my 15' daysailer. Also, when I rebuilt the headstock on my bigger boat, it tipped the blade just an inch or so aft, requiring me to re-set the rake of the mast to compensate.

 

[Rodbone]

Thank you Brian. All that makes sense. I'm still curious as to the sailing qualities of a catboat with a fixed keel that only draws 21 inches. I wonder if the problem will not be weather helm but that she sails great as long as the wind direction is never forward of the beam!

 

[Brian S]

Well, Rodbone, with respect to your question, which I will paraphrase as "How's she point?" I can say that I've sailed a Com-Pac 19, which is a shoal keel, almost full keel boat. The keel is cutaway in the bow and stern, and the boat lists at 24" draft, so that is about a 21" or less keel depth. It's a masthead rig with 150% genoa, not a catboat. Being as I grew up on dinghies, and have a small shoal keel/centerboard fractional boat now which feels dinghy-ish, I can say that I don't like sailing a Com-Pac 19. My boat will out point her, and will out tack her. Our lake is fairly narrow, so beating to windward up the lake is not too far off of short tacking. The day I was beating in that CP19, we'd lose all CMG on 2/3rds of the tacks, because the crew didn't understand genoa sheet timing, and would sheet down too hard too soon, causing the bow to blow downwind like a big barn door. ON THE OTHER HAND, I know people who LOVE their CP19s, and also the CP16 and CP23, which are similar keel designs. And they can beat to windward. So, just because a boat has a 21' keel draft doesn't necessarily mean they can't move to windward. But it might mean that I can't get them to move to windward well!

I'm sorry, that still doesn't answer your question about how a Cape Cod Cat 17 would handle. I think you should just call Cape Cod Shipbuilding and ask 'em. http://www.capecodshipbuilding.com/site/fleet.php?boat=capecodcat

 

[Ukeluthier]

I've sailed my Menger 19' catboat for three years now, and have become comfortable with the weather helm thing and how to control it. With a traditional catboat with a centerboard there are two basic tactics:

1. As has already been stated, use the centerboard only when going to windward. The more the wind comes on the beam or farther aft, the less centerboard you want down. None at all when broad reaching or running.

2. As the breeze stiffens, raising the centerboard may not be enough to prevent significant weather helm when reaching or running. You must reef to prevent the boat from becoming overpowered and uncontrollable. With a good jiffy reefing setup, this isn't too much of an inconvenience, and the boat will sail faster and more comfortably.

With a fixed-keeled catboat with no centerboard, you obviously lose the flexibility offered by the first technique. However, with a draft of only 21" (my Menger draws 22" with the board up), you obviously don't have much of a keel. I suspect it would be comparable to sailing my Menger with the board removed. It would do fine on a reach or run, but wouldn't point well at all.

 

[LloydB]

I don't think the purpose of the centerboard is to prevent weather helm but is instead to minimize lee travel. To sail a broad reach 90 degrees to the wind I'd think you would want every tool at hand to not drift leeward. Having said that I still don't have an intuitive handle about VMG and it would be helpful to have a rule of thumb for that?

 

[Snotter]

My first sailboat was a cold-molded, plywood catboat (15' length, 7' beam). It was very easy to sail. I lost control of it once in a mooring field in camden's outter harbor when the wind puffed. The weatherhelm made the boat uncontrollable and I T-boned a yacht as a result. I since learned that you can very quickly reduce sail by scandalizing the rig (dropping the gaff peak). The catboat is a single-handers dream.

P.S. after T-boning the yacht (which looked brand new) I called the owner and talked to his wife. She was so afraid how here husband would react to the news that she never told him. She took the boat to an expert in gel-coat repair without her husband knowing and I paid the bill--The lord works in mysterious ways.

 

[Ukeluthier]

I don't think the purpose of the centerboard is to prevent weather helm but is instead to minimize lee travel. To sail a broad reach 90 degrees to the wind I'd think you would want every tool at hand to not drift leeward. Having said that I still don't have an intuitive handle about VMG and it would be helpful to have a rule of thumb for that?

You obviously are unfamiliar with the vagaries of catboat sailing, then. Using the centerboard to balance the helm on catboats is standard operating procedure. Lots of techniques used on catboats seem foreign to sailors accustomed to modern sloops. For example, when pointing, the boat is sailed very "loose," that is, the boom is never sheeted in beyond the corners of the transom, let alone pulled to weather with a traveler as on a sloop. This is counterintuitive to a sloop sailor, but guarantees the best VMG to windward on a catboat.

Most cruising catboats have a sufficient amount of fixed keel to prevent excessive leeward drift on a reach without the centerboard.

 

[LloydB]

Uke thanks for your reply and wonder if a daggerboard and centerboard would act the same when reduced.

 

[Ukeluthier]

You're welcome, Lloyd.

A daggerboard won't have quite the same effect for balancing as a properly shaped centerboard. Because a centerboard swings from a pivot at its forward end, the center of lateral resistance (CLR) moves aft significantly as the board is raised. It is the balance of forces between the wind on the center of effort of the sails and the water on the center of lateral resistance -- along with underwater shape of the hull as it heels -- that determines whether and how much weather helm a boat will have.

A daggerboard, on the other hand, lifts straight up without significantly changing its own CLR. Because the CLR of the whole boat is determined by the sum of forces acting on the profile of any fixed keel, the hull itself, and the rudder as well as the daggerboard, raising it might change the balance a little bit.

Here is a diagram that may help with visualization:

 

[Ukeluthier]

Sorry, the diagram didn't load.

Let me try to attach it.

 

[Brian S]

Uke is correct that raising a daggerboard won't affect CLR the same way as raising a pivoting centerboard will do (and I would wager a pivoting high aspect centerboard will change the CLR more than a pie wedge centerboard.) Even so, raising a daggerboard will produce less lift. While lift prevents the boat moving sideways, which is good, it also introduces a rotating vector complementary to the heeling vector of the sail. This is why in my example with Lasers, lifting the daggerboard a bit can depower the boat allowing for less heeling and hiking. However, this can be at the expense of pointing and CMG, if one were to raise it too much allowing for too much leeway.