I recently bought a 1991 Hunter 37.5 Legend and I need to replace the depth finder transducer. I am told I will need to have my boat hauled out in order to install it in the same location, so I need to order one before haul out. I do not know the size of the original through hull so I can order the correct size to replace it. The manual says it is a ST50 but does not give the size of the through hull, so I need to make sure it is the correct one. If any Hunter Legend owners can advise me on this I would be most grateful.
Transducer through hull size
- Thread starter Suntala66
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,945
A common size for the through hull on a transducer is 2". That does not mean your transducer is 2". You are best advised to measure your own with a caliper to identify what the hole size is not what was used on another boat.
Here is the page from Raymarine showing a variety of different transducers. All of them can work with your ST50.
www.raymarine.com
Best is measure then order.
Here is the page from Raymarine showing a variety of different transducers. All of them can work with your ST50.
Instrument Transducers | Raymarine
Raymarine instrument transducers accurately and reliably record depth, speed, temperature, and wind for Raymarine i40, i50, i60, and i70 series marine instruments. Explore the range here.
www.raymarine.com
Welcome to the forum and congratulations on your new sailboat!!
Thru hull should be 2-inch diameter and the transducer should be retractable. Confirm the diameter, manufacturer (Airmar?) and model.
Thru hull should be 2-inch diameter and the transducer should be retractable. Confirm the diameter, manufacturer (Airmar?) and model.
Last edited:
Time to go modern and install an "in-hull" depth transducer.
Transducers are usually an extra to the display instruments so you can hold on to your display if it's not too old.
Transducers are usually an extra to the display instruments so you can hold on to your display if it's not too old.
You will need to measure it from inside the boat. While most modern through hulls are 2" in the past they have been larger and smaller.
Depending on the brand and model, there may not be a replacement transducer. Let us know the brand and model and we can give you better advice.
Buy the instrument of your choice with the transducer(s) and if the existing hole is a tight fit, use it as is. If the existing hole is too large, then fiberglass up the too big hole and recut another hole to fit the new transducer size. If your existing hole is smaller than the hole needed for the new transducer, then make the hole bigger. To do that, get a hole saw the size of the existing hole and have someone inside the boat place a piece of wood over the hole and hold it in place and then drill out the pilot hole into the wood from outside the boat. A long piece of wood works best because your inside person can place each of his/her two feet at the ends of the wood with no worry that it will move because pressure will be applied to hold it in place, and not worry about drilling a hole in a foot. With the wood inside still in place and secured with the pressure of the feet of your inside person, you can use that pilot hole to drill out the larger hole saw size. Obviously the boat has to be out of the water and also you need to use the appropriate caulk to bed the new transducer(s).