1/72 Skipjack and R & R Engineering WTC question

[g2tiger]

OK, I need some advice. I have the R&R engineering WTC which works ok save for the pump. It slowly leaks water past the pump into the ballast tank. So i was avoiding work and I was just cruising the web and saw Bob's video (https://www.youtube.com/watch?v=j0Ye35-EAfc) on the same model and WTC (1/72 skipjack and WTC) and have a question or two. In the video Bob shows that the air intake goes up to the sail and then through a smaller diameter tube disguised as an antenna. He states/says the smaller diameter tube acts as a control of sorts to allow control of filling and emptying the ballast tank. In my model water gets past the pump when I leak check the WTC holding the vent above the water with the air tube in the sail. I can blow into the tube or draw air and there appears not to be any resistance. I have a spare pump of the same kind and it appears to be the same with no resistance. What am I missing? I can install a smaller tube like in the video , but will that help? Looking for guidance. If possible some pictures would be helpful, I'm an adult learner :) Attached some pics of the model for fun, comments welcome.
I hope to have it ready for SubFest 2024.

[bwi 971]

The leaking of water through the pump is called backflow and is normal for pumps other than peristaltic pumps . I don't know what type of pump they are using—perhaps a gear pump? In my opinion, the only way to avoid this without using a solenoid valve is to have the suction/filling line higher than the water surface when the boat is surfaced.

Or, you can ignore it and empty the tank once in a while if you stay on the surface for a prolonged time.

Maybe reach out to Ron of R&R?

Below my layout.



Grtz,
Bart

[JHapprich]

What Bart said. The filling intake has to be above the waterline when surfaced. I don't use valves. A piece of silikon tube reaching from the high-up intake in the endcap into the keel area underwater will work.

Gear pumps leak. That's normal.

Jörg

[g2tiger]

Thanks gents, good information. I did have the standard intake connected toa silicone tube to the schnorkel mast which is way high above the waterline. But the pump still allowed water to trickle into the WTC. Ron said he would send a second pump but I declined as he also said I should check how the ball float component was mounted in the sail. I did try to put that component into the correct orientation but I was still getting water into the tank. When I get back home I will take a few photos and perhaps show what is going on. The main reason I am trying to fix it is because the amount of water passing the pump is enough that the model would most likely be submerged after about 4 or 5o minutes. I will also contact Ron again for guidance.

Bart, I like the look of your anti blow back set up. I think I understand how it will work and may be able to incorporate it into my WTC if needed..

[RCSubGuy]

It's going to leak, but in practical application, you'll never notice. The rate of leak is so insignificant that you'll only run into issues with it dropping from surfaced to submerged trim over the course of an hour or so.

The intake restriction worked absolutely perfectly with that Skipjack, and removes the complication, space requirement and potential failure point of the snorkel valve.

[g2tiger]

RCSubGuy, thanks for the info. Ill tinker with her and see what happens. Looking forward to the SubFest. A bunch of us from Jacksonville FL will be attending. Should be fun.