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Posted (edited)

Hi guys,

I've just installed a new tranny on my boat. Left side is pretty level with the hull but right side is exposed about 5 cm due to the deep v angle of my hull. Will this cause a problem with drag?

Cheers

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Edited by VViCKiD
Posted

Drag won't be an issue but we'll see you a mile off with the rooster tail your going to make. [emoji6]. Your motor will get a wash down constantly which is not good.

Sent from my iPhone using Tapatalk

Posted

A suggestion before you start bolting more on the stern. I see from the picture its a glass hull and you have a large bung to the left of the transducer -- I presume there is probably a well in the hull behind the bung. If the bottom of your hull is solid glass in the well area you have an opportunity to mount the transducer inside. I have done this and I have nothing projecting from the back of the hull - no rooster tail, no drag, nothing to snag, nothing to damage and no discernible loss of signal or performance. I can sound bottom at Browns and can read bottom up to near WOT.

If interested - to test this approach, fill some salt water in the well, place your transducer in there and put a wet sand bag or something similar on top to keep it weighted down. Take the boat for a run. You can play around with the position of the transducer within the limits of your well size. If you like the result, note the position of the transducer and fibregalss resin it into place. As fibreglass and resin are the same density as water they do not impact performance - however if you use silicone it WILL significantly reduce transducer performance.

I understand it is a bit of a pain when you want to change transducers/systems (I've changed mine once in 15yrs) - but consider how often do you do that vs how trouble free a working through hull set up can be.

Posted

Thanks for the advice zmk1962. Lucky I've made a fibreglass installation plate at the back (so I don't really care if I have to drill holes).

I'm quite curious with your installation though. Wouldn't the thermometer fail to work ?

Posted

True, it will read the temp of the water (and there is always some water) in the bottom of the hull which will stabilize with outside water temp over time - so in the purest sense there will be a temp reading delay with the thru hull set up. But practically I have not seen much difference. Since my sounder also accepted and external Temp/speed impeller in the Aux port I ran with that for many years -- on a few occasions early on we even used the deck wash to fill up the well and compare what it was reading previously and the temp of the fresh water we had added to the well (with the bilge going). The difference I noted was negligible and going forward I was happy enough to just use the thru hull.

I have a deep V so it does sit deep in the water at the back.

PS - I eventually disconnected the impeller and ext temp source as I now use the Aux port to send an NMEA GPS location signal to my VHF radio - flick of a button and the VHF transmits my current location.

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