Raw Water Pickup Placement

[pelagic2530]

As part of my ongoing 1700 overhaul, I'm installing a raw water pickup. I will be using a seacock with a traditional scoop cut to fit snug to the seacock base, mounted to a 1/2" piece of epoxy/mat layup ground flat to fit and epoxied into the bilge.

My question is in regard to the position of the seacock itself in the bilge. It will be on the Port side so as not to interfere with the transducer mounted to Stbd. However, in looking at pictures of installs on this page an others, it seems that most of them are located towards the aft end of the bilge compartment. I'm dealing with limited space in a very small bilge, despite having already installed the largest hatch that will fit, and the aft area of my bilge is pretty inaccessible. I'm wondering if there's any issue mounting the seacock at the forward end of the bilge compartment? This would be about 2' forward of the transom, with the livewell pump mounted directly to the seacock, the washdown pump mounted to the stringer aft of the seacock, and all hoses running aft and up out of the port side rigging passage. Does anyone here foresee issues with mounting the seacock further forward?

Additionally, due to the size of the bilge the furthest off centerline I can mount the seacock is about 6" off center. I've heard about issues related to cavitation produced by pickup scoops. Is this likely a sufficient distance to avoid cavitation, or is it likely to produce issues?

Any other advice related to installation is appreciated.

 

[PKS1801]

The disturbance from your pick-up will spread out in a vee, just like your boat wake. Putting it 2 feet forward will increase its width at the prop. Will it cause ventilation, I can't say. I was always surprised to see how many scoops Parker installed dead center, right in front of the motor.
Use a properly threaded seacock flange, straight threads on the bottom, tapered NPT on top. Some people, and some manufacturers, use a ball valve as a 'seacock', which results in screwing straight threads into tapered threads, resulting in a weak connection.

https://www.passagemaker.com/technical/troubleshooter-the-gatekeeper

 

[pelagic2530]

The disturbance from your pick-up will spread out in a vee, just like your boat wake. Putting it 2 feet forward will increase its width at the prop. Will it cause ventilation, I can't say. I was always surprised to see how many scoops Parker installed dead center, right in front of the motor.
Use a properly threaded seacock flange, straight threads on the bottom, tapered NPT on top. Some people, and some manufacturers, use a ball valve as a 'seacock', which results in screwing straight threads into tapered threads, resulting in a weak connection.

https://www.passagemaker.com/technical/troubleshooter-the-gatekeeper

PKS, thanks for the link. I'm using a Groco seacock and a corresponding Groco pickup. My current plan is to proceed with the install, see if it causes a problem, and if so replace the scoop with a flush mount. in your experience, how does ventilation (thanks for the correct term) present itself from the operators perspective?

 

[warthog5]

I'm wondering if there's any issue mounting the seacock at the forward end of the bilge compartment?

You will be fine.....The reason you see them farther back is strictly a access thing.

What pump are you going with? I use the Rule Dual port units. They make several models....1 has straight threads and the other NPT threads.

 

[pelagic2530]

You will be fine.....The reason you see them farther back is strictly a access thing.

What pump are you going with? I use the Rule Dual port units. They make several models....1 has straight threads and the other NPT threads.

Thanks Wart. I’m using a Johnson 500 dual port pump. Inlet is tapered 3/4” NPT and connects directly to the to of the seacock. What’s your preferred method of installation regarding the plastic threads in the metal body? Pipe tape, sealant, none necessary?