Mast tube drain

I am toying with the idea of draining the mast tube into the keel trunk. This would shed a few grams as my mast tube always seems to be full. I am concerned that the drain would allow air to be sucked down and affect the lift of the fin. Has anyone tried this?

Why not a little thump-pump on the deck with the suction tube at the bottom of the mast tube? Weed-wackers engines use the little pump to prime the carburetter. My force5 had a suction-type cockpit drain, but the check ball fell out and never really worked anyway.

There are lots of ways to shave a few grams of weight besides the water in the mast tube, like lighter batteries, servos, the receiver, the rig. You could even cut holes in the deck and cover with lightweight patches.

remember that you will only be draining the difference in water levels between the mast tube and the draft of the boat. In some instances the difference with the skiff type deck, is only 15-20mm.
I don’t think you would ever get enough speed to draw a vacuum and suck air into the fin slipstream, without some sort of opening on the bottom of the hull.

That’s true. On my Force 5 there was a fairing for the cockpit drain under the hull, and a ball-type check valve to keep the water from coming back in. Is it worth saving a few grams of weight to add a few grams of plumbing and a small drain tube sticking out the bottom?

Since my mast tube actually touches the keel trunk it’s just a matter of drilling a hole between the two so it would weigh less (ever so slightly) than without the drain. My mast tube holds 35 grams of water, 15 of which is below the waterline. So in light winds(when the mast tube would normally be empty) I would be up 15 grams but when the wind was up and the mast tube would normally be full I would be down 20 grams(depending on how fast it drained). Given my sailing skills this would make absolutely no difference to any results but this hobby is all about being anal isn’t it? It was just a thought. I’ve met people that would kill for 20 grams.

the hobby/sport is all about sailing. Some people build their own boat from scratch and some people buy a kit. Then you spend years learning to sail well. Then when you are a perfect sailor, you can start to worry about saving a few grams of weight.

Why is the water getting in the first place? Fixing a leak would be easier, and I really don’t think any sailor I know would worry about it, unless the boat was filling up with water

Hmmm, figure out a way to put a little flapper valve in there.

The mast tube is open at the top, it doesn’t get inside the hull. I have to drive 100 miles to sail with other people. So to fill the time in between trips I work on silly little things. A win is a win whether it’s by an inch or a mile.

You also said earlier"I don’t think you would ever get enough speed to draw a vacuum and suck air into the fin slipstream, without some sort of opening on the bottom of the hull."

I think that if you could pull the water past a flapper you could probably suck air into the slipstream. I just glued the deck on my latest boat so it’s too late for this one. I think I will try it on the next boat. It will be a small hole, easily filled if I see a trail of bubbles behind the boat.

Another thought. If I plugged the bottom of the mast that would displace some of the water in the tube.


Do not even attempt this…Some boats are designed to have any water that collect on deck to drain toward the mast tube…look at the Lintel, IOM. It is better to have any water that collects in the center of the boat. Holes to drain this are not a good idea. Just tilt the boat between heats or invert if you are concerned of any excess water in that tube…

Frank Vella
Lintel and ISIS IOM.


Perhaps a combination of plugging the mast foot coupled with a very close fitting mast tube would virtually eliminate any weight gain in the rough stuff? I should point out that I have no experience of mast tubes/keel stepped masts, so there could well be very good reasons why this won’t work!