Extra Thru Hull / new bilge pump

[Phil Spicer]

   Dave, have you thought about 2 bilge hoses going into a Y and use the existing thru hull? Put the Y higher than the thru hull so the discharge doesn't go into the other hose. Just another thought.

[Ed Shankle]

Dave, given the location of your raw water thru hull, where is the strainer and how do you access it? Just thinking that the typical one that most of us have may be more convenient for regular checks, cleaning, etc.
Regards,
Ed

[DaveBMusik]

Dave, given the location of your raw water thru hull, where is the strainer and how do you access it? Just thinking that the typical one that most of us have may be more convenient for regular checks, cleaning, etc.
Regards,
Ed

The strainer is still under the head sink, the shut off is near the shaft in the aft cabin access.
I inherited a wonderful, new Yanmar 3YM30 with a great install. I don't know the reason for adding a new intake.

[DaveBMusik]

   Dave, have you thought about 2 bilge hoses going into a Y and use the existing thru hull? Put the Y higher than the thru hull so the discharge doesn't go into the other hose. Just another thought.

I believe that is frowned upon as it removes the redundancy of running two pumps at once in an emergency

[KWKloeber]

   Dave, have you thought about 2 bilge hoses going into a Y and use the existing thru hull? Put the Y higher than the thru hull so the discharge doesn't go into the other hose. Just another thought.

I believe that is frowned upon as it removes the redundancy of running two pumps at once in an emergency

That's not necessarily true Dave - that a Y would negate using 2 pumps.  It depends on the Y size and relative height above waterline. First, I don't know the physical set up on a 34 -- so as a practical matter it may not work because you have nowhere to get height, and this is moot.  But, theoretically you can run 2 discharges in to one Y and thru one orifice restriction (thru hull.)  It all depends on how much head above WL is necessary to push flow x and flow X+  thru the thru the given size thru hull. 

Say the Y and thru hull are LARGE (12" dia) then there'd not be much issue dumping x and X+ into one.   It's essentially solving 2 simultaneous dynamic equations, with the height above WL being the same variable in both equations.  If the Y is located high enough, or there's a high loop above the Y (increase the gravity head to force more water flow thru the orifice) then one line won't back up into the other line.  Again you may not be physically able to do that.

One caution in all this thread (and not sure it applies here) is to avoid (read NOT USE) thin wall pipe (Say ABS OR white poly sink drain stuff) where it discharges to a thru hull or any fitting that may fall below WL (e.g, on a heel)."  (i.e., where the pipe is subject to seawater entry, not simply laying against the hull or happens to be physically lower than the WL.)   
At a minimum it needs to be Sch 40 PVC pressure pipe (not DWV) and personally IIWMB I wouldn't use ANYTHING but Schedule 80 PVC if subject to sea water (if I couldn't use approved hose.) At the thru hull connections (say a barbed tailpiece) it should NOT be ANY kind of PVC (CTY notoriously used gray PVC hose barbs on thru hulls,) but it needs to be marelon or equivalent glass-reinforced type.  PVC (for good reason) is NOT approved for below WL barbs.

-kk

[Stu Jackson]

Re: piping material.  A bilge pump hose to the transom is not underwater.   Anything connected to a thru hull seacock would be.

[KWKloeber]

Re: piping material.  A bilge pump hose to the transom is not underwater.   Anything connected to a thru hull seacock would be.

Ahhh yes, thanks Stu -- I should have been more explicit -- MEA CULPA.

Check my statement to say not simply "below WL," but

One caution in all this thread (and not sure it applies here) is to avoid (read NOT USE) thin wall pipe (Say ABS OR white poly sink drain stuff) where it discharges to a thru hull or any fitting that may fall below WL (e.g, on a heel)."  (i.e., where the pipe is subject to seawater entry, not simply laying against the hull or happens to be physically lower than the WL.)   
At a minimum it needs to be Sch 40 PVC pressure pipe (not DWV) and personally IIWMB I wouldn't use ANYTHING but Schedule 80 PVC if subject to sea water (if I couldn't use approved hose.) At the thru hull connections (say a barbed tailpiece) it should NOT be ANY kind of PVC (CTY notoriously used gray PVC hose barbs on thru hulls,) but it needs to be marelon or equivalent glass-reinforced type.  PVC (for good reason) is NOT approved for below WL barbs.

Good catch!!

ken