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Tech Tip

Marelon Thru-Hull/Seavalve Installation

Note:  This Installation sheet ONLY applies to Marelon Integrated Plumbing System(Series 93) Valves

This marine seavalve is made of MARELON®, a glass reinforced nylon composite. It exceeds standards for use set by the U.L. (Underwriters Laboratory) and the American Boat and Yacht Council (A.B.Y.C.). It is a complete system including thru-hull fitting, valve body, and hose connector.

HULL OPENINGS

Prepare a clean round hole in the desired location and of the appropriate diameter for the chosen thru-hull fitting per the requirements below. For flush head thru-hull fittings only, make an external 45 deg. chamfer ¼" deep. If the recommended backing block is used, a uniform hole diameter must extend through the backing block.

½" and ¾" Thru-hull/seavalves – 1-1/8" hole

1" and 1-1/4" Thru-hull/seavalves – 1-1/2" hole

1-1/2" and 2" Thru-hull/seavalves – 2-1/8" hole

BACKING BLOCKS

A backing block or an equivalent structure molded integrally into the resin/glass hull lay-up is required for installations on all non-flat hull surfaces. This is also recommended procedure for flat surfaces as well. For wood backing blocks, white oak is a commonly used wood. There may be other suitable materials as well.

THRU-HULL FITTING LENGTH

The thru-hull fitting, when fully installed, should project beyond the internal hull/backing block surface no less than ½" and no more than 1-1/4".Engagement of five (5) full threads will generate the full loading strength of the thru-hull/seavalve assembly, which is well in excess of the 500 pounds, required by the U.L. and A.B.Y.C. standards.

BEDDING

The thru-hull fitting’s external flange should be properly bedded when the fitting is inserted into the hull. The exposed male threads protruding from the inside of the hull should be applied with bedding material as well. The surface of the female threaded round king-nut portion of the valve, which interfaces with the internal hull surface, may well be bedded also, but it is not an absolute requirement and the loading strength will not be impaired if it is not done. Bedding compounds such as 3M’s #5200, Sikaflex or Boatlife are to be recommended as well as others that are equally suitable.