Thanks to all who have reponded to my original question about owining an Oday. Could somebody tell me a little bit about the different types of keels and how they work? Thanks!
Keel Questions
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Differnent Types
Here's a primer based on my general knowledge. Don't take it as gospel, just a guide! In general, all keels are designed to be weighted and keep the boat upright. They also will usually have some sort of hydrodynamic properties to provide lift. Importantly, they also prevent side slippage to leeward. Different keel designs can affect things like pointing ability, stability, and speed. Full Keel - not found often on modern boats. The keel is the full length of the boat. Very stable. Not so speedy. The rest of the keels discussed are "cut away", or non-full keel designs. Common draft: 5-6 feet. Fin Keel - deep draft. Is either generly uniform in thickness (like a shark fin) or is a bulb. The bulb keel has a thin part attached to the hull, and the bottom has a weighted portion to keep the weight down low. Best for ocean going craft, and racing craft. Advanced bulb keels can swing to the windward side to reduce heeling and improve performance. Common Draft: 4-6 feet. Wing Keel - Less draft than a fin keel. Like a relatively short fin keel. Less draft than a fin keel - in between a fin and a shoal keel both in terms of performance and draft. It has two "wings" that stick out from the side of the keel bottom to provide lift for port or starboard tacks. Better than a fin keel for coastal cruising. Common Draft: 3 feet. Shoal draft or stub keel - what is on the O'22. A shallow draft keel, with more ballast than a similar but longer keel, or a centerboard keel, because the weight is closer to the hull. Good for sailing in shallow water areas, but is more prone to side slippage because there is less keel area to press laterally against the water. Common draft: 1.5-2 feet. Centerboard keel - Often like a stub keel with a retractable board that swings from a slot. Combines the benefits of a wing or fin in terms of resistance to slippage, but allows for sailing in shallow water. Centerboards are pulled up with a rope, which can wear out and break, and can get stuck, and the trunk takes up room in the boat. Common draft: 1.5-2 feet (retracted); 4-5 feet extended. Water ballast - found on Hunters. Launch the boat and the keel will fill with water (vs. fixed lead or iron ballast). Reduces weight while trailering. But you need more water to equate to lead ballast. Common draft: I have no clue. Retractable (fin) keel - new on Seawards. A bulb fin keel that is good for deep water, but will retract vertically into the cabin by means of an electric winch in shallow water. (Very cool in my opinion - the 25 and 30 foot RK model Seawards can float in something like 18 inches of water.)Common draft: 18 inches - 5 feet. Center or dagger board - found on small craft and catamarans (think Sunfish and Laser). A long non-weighted board is shoved through the hull to counteract slippage and help keep the boat upright under sail. Common draft: 6 inches (board out)- 3 feet(board in). Swing keel - I think this is kind of like a centerboard, but weighted heavier to get the ballast down low. I'm a little fuzzy on this one. Common Draft: 1.5 feet - 4 feet??? I'm sure a missed something here, so feel free to add or correct! Brad
Here's a primer based on my general knowledge. Don't take it as gospel, just a guide! In general, all keels are designed to be weighted and keep the boat upright. They also will usually have some sort of hydrodynamic properties to provide lift. Importantly, they also prevent side slippage to leeward. Different keel designs can affect things like pointing ability, stability, and speed. Full Keel - not found often on modern boats. The keel is the full length of the boat. Very stable. Not so speedy. The rest of the keels discussed are "cut away", or non-full keel designs. Common draft: 5-6 feet. Fin Keel - deep draft. Is either generly uniform in thickness (like a shark fin) or is a bulb. The bulb keel has a thin part attached to the hull, and the bottom has a weighted portion to keep the weight down low. Best for ocean going craft, and racing craft. Advanced bulb keels can swing to the windward side to reduce heeling and improve performance. Common Draft: 4-6 feet. Wing Keel - Less draft than a fin keel. Like a relatively short fin keel. Less draft than a fin keel - in between a fin and a shoal keel both in terms of performance and draft. It has two "wings" that stick out from the side of the keel bottom to provide lift for port or starboard tacks. Better than a fin keel for coastal cruising. Common Draft: 3 feet. Shoal draft or stub keel - what is on the O'22. A shallow draft keel, with more ballast than a similar but longer keel, or a centerboard keel, because the weight is closer to the hull. Good for sailing in shallow water areas, but is more prone to side slippage because there is less keel area to press laterally against the water. Common draft: 1.5-2 feet. Centerboard keel - Often like a stub keel with a retractable board that swings from a slot. Combines the benefits of a wing or fin in terms of resistance to slippage, but allows for sailing in shallow water. Centerboards are pulled up with a rope, which can wear out and break, and can get stuck, and the trunk takes up room in the boat. Common draft: 1.5-2 feet (retracted); 4-5 feet extended. Water ballast - found on Hunters. Launch the boat and the keel will fill with water (vs. fixed lead or iron ballast). Reduces weight while trailering. But you need more water to equate to lead ballast. Common draft: I have no clue. Retractable (fin) keel - new on Seawards. A bulb fin keel that is good for deep water, but will retract vertically into the cabin by means of an electric winch in shallow water. (Very cool in my opinion - the 25 and 30 foot RK model Seawards can float in something like 18 inches of water.)Common draft: 18 inches - 5 feet. Center or dagger board - found on small craft and catamarans (think Sunfish and Laser). A long non-weighted board is shoved through the hull to counteract slippage and help keep the boat upright under sail. Common draft: 6 inches (board out)- 3 feet(board in). Swing keel - I think this is kind of like a centerboard, but weighted heavier to get the ballast down low. I'm a little fuzzy on this one. Common Draft: 1.5 feet - 4 feet??? I'm sure a missed something here, so feel free to add or correct! Brad
swing keel
The "Swing Keel"has a short stub keel always in place(2 or 3 ft. deep) then is just like a center board keel except it has the advantage of no center board trunk in the cabin and or cockpit.but the dissadvantage of not being capable of sailing in as little as 10 in. of water.and harder to launch from a trailor!! everything on a sailboat is a compromise !!
The "Swing Keel"has a short stub keel always in place(2 or 3 ft. deep) then is just like a center board keel except it has the advantage of no center board trunk in the cabin and or cockpit.but the dissadvantage of not being capable of sailing in as little as 10 in. of water.and harder to launch from a trailor!! everything on a sailboat is a compromise !!
swinging keels
The biggest difference with the swing keel is that the swinging keel itself is the boat's ballast. With the keel/centerboard combo, the ballast is in the stub keel and the centerboard is relatively light.
The biggest difference with the swing keel is that the swinging keel itself is the boat's ballast. With the keel/centerboard combo, the ballast is in the stub keel and the centerboard is relatively light.
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