Through Hull

The force exterted at the top of the pipe by the momentum caused by reeling of the boat in something like 20 knot wind is little less than 3 Newton. A centimeter of correct weld holds roughly ton static.

 

You can do the trough hull like that, I have seen it before. It's better to have two attachment points for the pipe, do a bracket somewhere. This is for vibration, not bending moment.

One of the unexpected consequences of this arrangement is sound generation, water enters the pipe from below and changes height when the boat heels in waves. The air column above is compressed and the whole thing becomes a flute, howling away. If you have a water siphon above the valve you will have gurgling sounds, in heavy seas water can splash upwards. The solution is to close the valve.

 

Thanks. I would just weld piece of flatbar between it and side? That would do it, right.

 

I’m only guessing at to the reasons it is not allowed in an effort to help you. I’m not presenting an argument or nonsense. My surveyor made it clear to me no hard piping all the way to the hull was allowed. He actually emphasized it in a pre-survey meeting. Maybe more critical in frp construction as frp does not easily transistion to things like steel or pvc.

If you insist on hard piping to above the waterline, like I said above, I’d also bracket it so noone can accidently put a side force on the pipe at sea.