Sink Drain Thru Hull

[KWKloeber]

John : You are correct!!  There is no pressure or suction - just a gravity feed.  The 1" hose neatly clamps on to the 3/4" barb.

It is just like the 5/8" raw water hose clamping on to the 1/2" thru hull!!

A few thoughts

1/2" THs have either  1/2 thread x 1/2 hose tailpipe or a 1/2 thread x 5/8 hose tailpipe.
A 5/8 hose should have a 5/8 tailpipe!!

[KWKloeber]

Ken : The 3/4" barb is already on the TH, it's below the waterline and the sink drains marvelously - so why change it ????

A thought

Because perhaps it's the proper thing to do - match barb size to hose size??  Other than that, no there's no reason LOL.

[Ron Hill]

Guys : I got the slightly oversize hose on to a slightly smaller barb from -- Catalina!!! 

That's the way the factory plumbed the raw water 5/8" hose to the engine that is attached to the 1/2" thru hull barb!!  They did that will all of the MK I C34s and C36s  and MAYBE ? even with the C30s? with the M25XP engine???  That's a few thousand hulls!!! 

A thought