Just Bought My First Boat - About to Give it to a Scrapyard

Sep 18, 2024
11
Catalina 30 marina park marina
How hard would it be for me to replace/install a through hull fitting below the waterline?
 

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
21,846
CAL 35 Cruiser #21 moored EVERETT WA
It is not a difficult task. Are we taking an old one out and replacing it with new one?
 
Jun 21, 2004
2,612
Beneteau 343 Slidell, LA
How hard would it be for me to replace/install a through hull fitting below the waterline?
Obviously, the boat needs to be out of the water. Because you haven't done this previously, I would estimate 60-90 minutes. Decide what components that you plan to replace (thru hull, valve, tailpiece, & hose); should replace all components if they haven't been replaced in past. Also check to determine if there is a wooden "backer plate" between the interior of the hull & thru hull nut; if it is present & rotted, it should also be replaced. Cut off the outside/mushroom surface of the thru hull fitting with a powered grinder & abrasive wheel or disc. Disconnect the hose on the inside of the boat & pull the remainder of the thru hull fitting, valve, & tail piece from inside the boat. (approximately 15 minutes). Clean up the hole in the hull & remove all remaining sealer with sand paper & wipe with acetone. Dry fit new thru hull fitting & valve to ensure the valve handle is oriented in a convenient location. I mask the hull surface surrounding the hole to ease cleanup of excess 3M4200 that I use to seat/seal the thru hull fitting (40 minutes). I use Permatex pipe thread sealant on the remaining thread surfaces. Preferrable to have someone on the outside holding the fitting in position to prevent movement while you are tightening the thru hull nut on the inside of the boat. Install the valve & tailpiece (30 minutes). Allow the entire assembly to set up for at least 24 hours; be sure to read 3M label for ambient temperature setting times. Install the new hose & two clamps on each hose end. (15 minutes) & be sure to check for leaks when the boat is splashed.
This job can be done in 30-40 minutes by an experienced worker. Also, you can do this without a helper if you have the appropriate step wrench; however, I recommend a helper. This procedure is for removal & replacement of bronze fittings. If your Catalina has Marelon fittings, you should consult with a source familiar with those fittings.
Be aware that everyone has their favorite sealants to perform this task, I only mentioned what I prefer; however, there are many sealants to consider.