Installing big thru hull transducers...have you done it?

[Raider Ronnie]

Installed a handful
My BHM has an Airmar b260 the blue fairing block is huge (2ft long)
Location for the install is key.
Then you have to figure the dead rise angle, mine was 5 degrees. Being a downeast boat 5 degrees is not much, a planing hull will be more.
Mounted it in a tilted fence band saw for the cut. The piece that is cut off is the inside backer for when you bolt it together.

[nightfighter]

[QUOTE=Raider Ronnie;901443]Installed a handful
My BHM has an Airmar b260 the blue fairing block is huge (2ft long)
Location for the install is key.
Then you have to figure the dead rise angle, mine was 5 degrees.
Mounted it in a tilted fence band saw for the cut. The piece that is cut off is the inside backer for when you bolt it together.[/QUOTE]

A critical piece to consider. Good post, Ron. While the saw is set up, cut a second block of wood or plastic as a back up. Sometimes the cut off of the blue block gets dinged up, or won't fit in the bilge between stringers. I have also seen the inside backer cut too thin. In that case, just add a block to the backer. May have to countersink to reach the transducer for securing. Use the cutoff as template BEFORE installing. (Had to do this fix for a friend who had already installed with 5200, so I was drilling blind from the inside...)

[beamie]

Sandman,

Don't let this scare you, if you are handy it really isn't a big deal.

I installed a similar ducer as Ronnies, just a bit shorter maybe a 15" B744.

I used epoxied plywood as a backer, my location was a zero deadrise spot on a stiffner rake.

Is is important to dryfit this together and actually put everything in the hole including the paddle wheel if you have a speed transducer too. Short story......I have everything ready to go and fit it, then found out shortly after that my speed attachment wouldn't bottom out and seal for the backer block was too thick. So picture wet 5200 on everything snaking cable thru nuts and everything to take this apart to install a thinner block. Yeah it was a bit messy to say the least and just a few cuss words......

As for ducers with the speed paddle wheel I wouldn't bother spending the extra money for this thru the water data. You really don't use it and is just approximate anyway.. Just another thing to maybe go wrong in the bilge.

[Raider Ronnie]

Some good points by Beamie
Dry fit as many time as necessary before installing with either 4200 or 5200. That stuff can make a mess.
Be sure to remove all bottom paint, sand, wash with acetone areas to be sealed, inside & out.
Should you be removing an old thru hull & need to drill bigger hole (think mine was 2inch) hot glue a scrap piece of wood inside to have a pilot hole for correct bigger hole saw size. Hot glued wood will pop off easy enough later.