Hello All, I have a 94 Catalina 22 with a wing keel (not an MK II) that I am going to install an depth sounder. In order to program the sounder to register the distance under the keel vs. the hull I need to know the dead rise from the keel to the hull. This is given as an angle and the boat is in the water and It would be hard to take the measurements as is. Does anyone have the information concerning the dead rise on my boat?
94 Catalina 22 Dead Rise
- Thread starter sigsgmret
- Start date
Yes, I know the draft. However, this is not the "dead rise". The dead rise is expressed as an angle from the bottom of the keel to the water line.
OOPS, my bad. the dead rise is measured as an angle from the bottom of the keel to the chine, not the water line.
@sigsgmret this feels like one of those events when "perfection" is the enemy of good.
What level of perfection are you seeking? A depth sounder is most often used on a sail boat to return data that keeps the boat floating and not stuck. If the water depth is 5 feet. Your keel is 3 ft and the depth sounder reports to you there is 1 foot of water beneath the keel then you are still floating. If the bottom is typical there are ripples of 6-8 inches in the sand. You are still floating because you are using good not perfection.
So perhaps setting the sounder to 3 feet or even 4 feet.
In most sounders the issue of Deadrise is managed by adding a wedge to the sounder where it connects to the hull. The wedge corrects for the angle of the hull at the location used to install the sounder so that the sounder transmits a vertical signal into the water. Note sounders send a signal as a cone beneath the boat. If it is angled it will send a response back to the transducer giving you the distance at that angle to what ever it bounced off.
What level of perfection are you seeking? A depth sounder is most often used on a sail boat to return data that keeps the boat floating and not stuck. If the water depth is 5 feet. Your keel is 3 ft and the depth sounder reports to you there is 1 foot of water beneath the keel then you are still floating. If the bottom is typical there are ripples of 6-8 inches in the sand. You are still floating because you are using good not perfection.
So perhaps setting the sounder to 3 feet or even 4 feet.
In most sounders the issue of Deadrise is managed by adding a wedge to the sounder where it connects to the hull. The wedge corrects for the angle of the hull at the location used to install the sounder so that the sounder transmits a vertical signal into the water. Note sounders send a signal as a cone beneath the boat. If it is angled it will send a response back to the transducer giving you the distance at that angle to what ever it bounced off.
Yes I understand having water below the keel means I'm still floating. The rule of thumb I use for my comfort level is 10' below the keel. However, I have exchanged a few emails with the folks at Garmin to see if they have a recommendation as to the type of depth sounder and transponder. The person I exchanged emails with said he needed to know the dead rise of my boat before he could make an accurate recommendation. So that's the reason for my request.
Guy at garmin is a dweeb. Find your depth at slip, subtract your draft and then set your depth at what you want to be below the keel as "cushion:" I set mine so it shows the depth as 4 feet less than my actual draft because my transducer is just forward of the keel and that gives me warning to veer off before I am actually in any danger.
That's a good idea being that my present transducer (now tits-up) is a thru-hull just behind the keel where the boat is flatter but experiences some turbulence from the keel. The new one will be in-hull forward of the keel before the V gets too drastic. Thanks.
Yep its nice to know shallows are a coming , guys with transducer hanging off stern got big surprise on sailboats. For flat bottom power boys they only care if motor lower unti hits at 30 knots. But us sailors tend to be a little more proactive in placement of transducers and also bright enough to reduce speed when it shows shoaling occurring.
The wing keel on my Capri 22 is 18" from bottom of hull to bottom of keel. I believe it is the same keel, different boat. Ask Crazy Dave, he knows.