Water Tank Access Port Installation

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Oct 14, 2005
2,191
1983 Hunter H34 North East, MD
After finding residue clogging my faucet strainers, I decided it was time to cut an access hole in the port-side water tank top of my H34. I chose a 8” OD Beckson clear-top port for this project. A tape measure was used to determine the tank top’s dimensions and then to approximate the center in order to locate where to install the access port.

Once this was determined, a vibrating saw was used to cut a square lid out the seat top, below which the access port was to be installed. Pictured below are some of the tools used to complete this project. Not shown is a scroll-head jigsaw that enabled the actual tank cut-out to be made.

(Picture 1)

Once the location was determined, a vibrating saw was used to first define the corner cuts, then to link them to create a square cut-out in the port-side settee top that would become the lid when the project was completed.

(Picture 2)

With the seat-top panel removed, the Beckson port itself was utilized to lay out the cut line circle. A scrolling-head jigsaw was used to make the cut because it allowed the body of the saw to be centered in the opening while the saw was rotated to make the circular cut-out.

(Picture 4)

With the tank top cut open, a hand pump was used to remove all the water it could before a sponge was used to remove the last amount. The tank was found to contain a residue of rust, which must have come from the marina’s old dock water system. Also noticeable on the tank’s walls were the various water levels that had sat in the tank at different times.

(Pictures 5 & 6)

The rust residue was wiped up and a “Magic Eraser” was used to remove all the stain lines. The Beckson access port was inserted in the tank opening and the first hole was drilled through the tank top, then tapped for the stainless machine screw’s thread pitch. A machine screw was installed to hold the rim in place. The rim was aligned and the next hole drilled was directly opposite the first one of the six to achieve an even fit. This process was repeated back and forth across the rim in the same manner until all the other holes were drilled, tapped, and fitted with the machine screws.

(Picture 7)

All machine screws were then removed and on the back side of the port’s rim a thick bead of silicon sealant was put in place. The rim was set back in the tank top in same position it was dry-mounted in and, one-by-one back and forth, the machine screws were inserted and hand started in the threads. Each opposite was carefully tightened down in the same manner that you would torque an engine head in place.

The tank material is thin, so over-tightening will strip out the threads. The trick is to just snug them up so that the silicone spreads out but is not squeezed out. Once the rim was installed, a small hand vac with extension hose was used to remove all the cutting and drilling residue and remaining rust particles.

(Picture 8)

To support the lid piece that was cut out, frame rails had to be cut and fitted.

(Picture 10 & 11)

The lid was taken home and passed through a router’s round-over bit on both sides to smooth the edges. All told, this project took about two hours to complete. It has made checking the tank’s water level a snap (of a flashlight’s switch), and will make winterization nearly painless.

(Picture 12)


 

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Feb 4, 2005
524
Catalina C-30 Mattituck, NY
Dan - Nice job! The PO on my boat installed the exact same access ports but they leak around the frame (where the port meets the tank). I tried sealing them up with 4200 and they still leak. If you don't mind me asking, exactly what kind of sealant did you use?

Thanks - Rob
 
Feb 21, 2008
408
Hunter 33 Metedeconk River
I did the same project at the beginning of the season. The Hunter 290 fortunately has an access panel in the wood, under the mattress in the forward bunk right about the center of the tank. I would suggest two changes in the procedure, and they not my original ideas. First, cut out the top of the water tank using a sharp Exacto type knife. It cuts relatively easily and there is no "plastic dust" that has fallen into the tank to clean up afterwards. Secondly, I used SS bolts with SS washers and SS nuts to connect the port to the top of the tank. No worries about stripping the plastic. I used Silicone for the Kitchen and Bath for a sealant under the port frame and made sure it squished into the bolt holes. All works well and no leaks so far. I tested it with water and red food dye to insure it was well sealed.
 
Oct 14, 2005
2,191
1983 Hunter H34 North East, MD
Rob & Leigh...

Rob: If I remember back to last May, I used GE kitchen/bath silacon that was labeled drinking water safe. You need to apply it as a generous bead and circle the screw holes to ensure a good seal. Don't squash all the sealant out when you tighten it down. My tank top even had a slight curvature in it that the port took out when tightened. So far no leaks.

Leigh: The tank needed a full cleaning out so debris getting into it wasn't a issue. I thought of using SS nuts/bolts when I found how thin the tank top was. Careful tightening kept the SS machine screw threads from being stripped out. Nuts & bolts were the back-up plan if the machine screws didn't work out.
 
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