True Blue
Here is a post from THT authored by Peter Braffitt that may help you decide. Are you looking at a B-260 with high speed fairing or a flush mount tilted element model?
Default RE: Airmar B-260 Install
Warthog5, I have to say that you have put an impressive amount of pride and effort into the B260 install, and it is very well done. My estimation is that you will have very good readings at nearly all boat speeds, but the face of the transducer will still be exposed to some flow noise as well as the boundary layer of turbulence running down the hull. The result may be some loss of picture quality at speeds above 12-15 knots, but again, overall I believe you will be very satisfied.
I am not trying to change your mind on the install but I would like to share some observations we have made while developing the high speed fairings that we offer. For a trilered boat, high performnace fairings do present some challenges due to their size. The disadvantage if you trailer the boat is that they do protrude past the hull so the mounting location has to be selected with the boat on the trailer first, and then a suitable placement selected that will produce a clean flow of water to the transducer. One of the most important features of the fairing is that it does hang the transducer below the turbulent boundary layer of water that flows down the hull's surface. This will give very good bottom readings at all speeds, as cleaner water is flowing over the transducer. The thin leading edge of the fairing gently slices through and parts the water and it's length allows the water to straighten or "get used to" the change in flow direction that the transducer creates, lessening flow noise. Without a high performance fairing, that sudden change of direction that the water has to make creates flow noise that actually generates noise at the same frequencies that the sounder operates in. This will show up as snow on the sounder screen, forcing you to make gain changes, which reduces screen detail. You will lose the ability to see as much below the boat as you could if the noise wasn't present. I could equate this to having a conversation with a friend on the boat when my head's above the windshield (say above 15 knots), versus having that same conversation when I am well below the wind shield. When I'm above the windshield, the rush of wind passing over my melon cancels out a lot of the conversation and forces me to listen much harder . When I sit down, I can speak softer and also hear the other half of the conversation much clearer. The windshield is acting as my fairing. Another advantage is the fairing also has a slim trailing edge to allow the water to gently re-form again as it flows around the back of the transducer. This is also designed to reduce flow noise, just like the front, but it also acts to reduce the chance of prop ventilation or intake cavitation.
My closing comments are that I am not trying to discourage your install and I think you are going to be pleased with the results. If a person has the room for the fairing block it is certainly a much more cost effective install (because your time is worth more than the cost of the fairing) and the fairing has some measurable performance gains over a flush install. I have never seen a loss of vessel performance on a boat from 28 feet up if the location was properfly selected and the fairing properly installed. A few weeks ago I was at a very prominent fishing boat manufacturer's facility a few weeks ago (name withheld to protect my a__) to do an install on a B260 and fairing with them. I got involved because their engineering team felt that the size of the fairing would affect steering, handling and top speed on a 32 convertable being built for a customer (who had requested they install one for him). When I got to their facility we did an extensive amount of testing and measuring before the install to establish the performance of the boat. After the install we duplicated the exact series of tests and there was no measurable change in any performance parameter of the boat. The best news came from the customer who took delivery a week or so later. In the trip home with the boat, he was able to read bottom clearly, even with the boat at full boot (33 knots).
I am eager to hear of the results when you splash the boat. If I'm in the area I might even invite myself aboard to bend some rod tips with ya'!
__________________
Peter Braffitt
Business Development Manager
AIRMAR Technology Corp.
Milford, NH USA
pbraffitt is offline Report Post