through hull fittings

[tommcat]

this could be an extremely stupid question but here it is anyway.
i'm putting 2 through hull fittings through the bottom of my boat for the ballast pumps. i though i knew which direction they are supposed to go but now i've been told by 2 people one way and one guy told me the opposite.
do they point forward so they'd get water forced into them while under way or backwards?

they are this style

[projectely4]

i would think it should be mounted so the smooth side is leading. the other way could end up putting alot of force on it at high speeds.

[Sodar]

Definately smooth side forward!

[P-hat_in_Cincy]

What kind of pumps are you using? If you don't have self-priming pumps then that thru hull should have the slots facing the bow. The "scoop" helps prime the pumps by using the forward motion of the boat while underway.

If you are using self priming pumps then that type of thru hull is not necessary.

Below is a picture of the hull of my boat. The slotted thru hull (on the right) is for my raw water pump and the slots face the bow. The "mushroom head" thru hull (on the left) is one of the two (in the bottom of the hull) I added for my ballast. The hole is where the 2nd thru hull went.

[P-hat_in_Cincy]

Here is a better picture of the "mushroom head" thru hull.

I'm curious as to why some think the slots should face the stern and not the bow? Here's the description from the West Marine site... "Discourages air locks in your water-intake lines at high speeds. Keeps water flowing at low speeds and debris out at any speed."

Here's a discussion on the topic.

PM me if you want to bounce ideas off me. I just completed my ballast install a few weeks ago.

[tommcat]

p-phat, your pic was one i was looking at. that slotted one is the factory fitting correct? i would think if MC faced it forward i should too?

i'm using self priming ballast puppy pumps. i know i dont NEED to face them forward but i thought it might speed up the flow a little.

[P-hat_in_Cincy]

Tomcat,
The slotted fitting is the factory thru hull for the raw water pump. It's good in it's application as water only needs to flow in one direction...in thru the engine.

Are you discharging the water out the side and/or thru a different thru hull? I'd think that while you may be helping with filling, you may be hindering with draining if using the same thru hull for supply and discharge.

[tommcat]

Originally Posted by P-hat_in_Cincy

Tomcat,
The slotted fitting is the factory thru hull for the raw water pump. It's good in it's application as water only needs to flow in one direction...in thru the engine.

Are you discharging the water out the side and/or thru a different thru hull? I'd think that while you may be helping with filling, you may be hindering with draining if using the same thru hull for supply and discharge.

good thought. yes i will be filling and draining through the same fitting, i didnt even think about that. thanks man

[P-hat_in_Cincy]

No problem! That's why these forums can be helpful.

FYI...our former X10 stock MC ballast system used the "mushroom head" type thru hull with a round disc strainer cover plate over it (it did not use the scooper type). It was located in the bottom of the hull like I did for our 205V.

[tommcat]

did you do a full test of your system yet? how much time does it take to fill your larger bags?
i'm running a fly high fat seat in the rear and wondering if one ballast puppy is going to cut it. if it takes too long to fill i'll run 2