Neatest ever ballast breather mod?

[restless]

Another cunning thought came to me as I gazed absent mindedly in my icicle rich mac26...
I've seen mods with ballast breathers, and understand that on newer macs than my 96 that the air vent is up under the vee berth. As I'm engaged in a bit of thru hull plumbing at the moment I'm remebering why I really hate these jobs.. exceedingly difficult to do so on a mac in an elegant way.
Unless..
20" forward of my centerboard trunk under the vee berth there is a flat topped pyramid type thing that looks like where a ballast valve could be. SSSSoooo.. if I were to plumb a pipe into that, with a 1/4 turn tap-valve running to a welded on stub tube leading into the mast support tube.. then at the turn of a tap I can vent outside without making any new hull holes. Also there won't be any splashing if I ignore the 'open valve' warning a little too long. I reckon it is an easier job to mod the pole than butcher the boat.
While there I'd put in my little float sensor low-level-warning device.
Can anyone think why this might not work?
Cheers!

[opie]

If you post a pic of your pyramid thing those of us with older MacX's can tell if what you see is what we have our vent in.

That being said, I do not understand why you feel the need to stick a tube on it. My ballast fills up to about 2 inches from the vent hole and I have left it that way for hours until I remembered to plug it. Unless I was sailing and leaning, no water comes into the boat. So why the plumbing need?

[restless]

I'll get a pic up a little later.
I've seen quite a few mods with folk who have put the vent outside just to avoid getting a load of stale air in the cabin. It would seem to make good sense to have a vent there (fwd) as otherwise there'll just be a large bubble of air slopping about. We love fair weather sailing, but sometimes it gets pretty lumpy. There are alot of headlands with some terrifying tidal races around here that can really throw the boat about. We also dodn't leave the boat in the water when not in use.. four seasons of that here and that's the price of our mac!!! Alot of launching.
I like to do a mod elegantly then sit back and be smug knowing that it probly couldn't be done better. I get a bit AR when it comes to engineering and sea safety
Also my admiral is (rightly) paranoid about the whole ballast thing anyway, so if the capt forgets to plug it even for 10 mins in harbour and gets caught out he'll get a really rough passage whatever the weather!

[Duane Dunn, Allegro]

It sounds like your mac was made right at the transition from the old rear vent to the forward vent. On older boats with the rear vent is at the steps (and the 2nd inlet valve), the forward area you describe is completely flat, no pyramid. I store my water tanks and batteries up there on my boat and it has no raised area at all.

I would guess your boat got made from the newer ballast tank mold but still had the vent being installed back at the ladder. I've heard of a few boats that were made just after the transition. They were made with the forward vent on the raised area, but still had the indent in the exterior hull just aft of the centerboard where the second fill valve is on the old boats. The second valve wasn't installed, but the indent was still there.

It seems that the factory makes a number of the major parts ahead of time in batches and stores them. Occasionally during model year traditions they end up with some incomplete sets of parts and have to mix and match creating half and half boats.

I'd love to have 2 more inches of vent height on my boat, as it is now you have to tend the vent when filling and if not promptly plugged when full water will overflow into the interior. Also as the last gasps of air vent out, the tank burps and squirts small fountains of water out the hole. As soon as I hear the burping start I plug the vent.

[restless]

Hej Duane.. brilliant info, the sort I like as it covers design through to production. Thank you.
This is my mystery indent...


So if I get this right, I'll be much better off putting this mod in and using the old vent as my level warning access plug. I know what you mean with the burping thing.. porta-pottie toilets do the same thing when you open the gate! I got an eyefull once.. thankfully on the mac. I narrowly avoided the same fate as some muddy water jumped up from that horrid toilet contraption!

[opie]

Interesting situation that the factory gave you. A pre-forward vent model 26X as well as a forward vent model 26X, all in one, except for the "bowl" that the factory installed around the vent hole that others may know the reason for. It is 4.5 inches deep and about 8 inches wide.



More pics here

[On edit, it looks like your "hump" is already raised...... right? Interesting. Can anyone else figure this out? Was Restless' model a trial mold that was later changed and not used again??? Plus, you have room for two fenders forward of the pyramid while I do not have that room. What is inside my boat there that you do not have. More mysteries...]

[eddy]

Hi my vent is installed under the Vberth i have a mac26X from 1998. This surpriced me, this should be in the newer mac26x.

[restless]

mysterious indeed.. forward of the fenders is a closed in flotation section. My hump is about 1 1/2 feet forward of the centerboard trunk... perhaps your venty thing is further up towards the flotation 'bulkhead'? Or you have more floaty stuff?

[J.Teixeira]

You may try a simple solution...

A pipe from the step valve hole to the head sink thruhull pipe...

[Kelly Hanson East]

I've heard of a few boats that were made just after the transition.

Wouldnt that violate copy exact and ISO 14001 .....

Elipses for you, Jim..........

[Don T]

Hello,
The history as I understood it:
1. Original boats had the small transom valve and raised bump vent forward. Customers complained it was hard and time consuming to fill the ballast in rough water.
2. Boat modified for center fill valve and vent located under the step. Forward bump vent not drilled.
3. Forward bump removed from tank as it was no longer necessary. Customers complained it was impossible to fill the tank completely resulting in ballast reduced by 200 lbs. Water splashes out of the center valve control rod and runs into bilges when filling. Aluminum washer (w/rubber seal) corrodes and fills the threads of control rod and customers thought the valve was tight when it wasn't causing water to fill into the bilges. (#2 boats suffered this as well)
4. Hole drilled in the cabin sole so water in the bilges will run out under foot so customers can see it and know they are leaking.
5. Transom valve enlarged (moved to opposite side) and vent moved forward again with no bump. Customers complained that with a fully equipped boat, water could overflow the forward tank vent and soak storage items at best and sink the boat if the stopper fell out or was loose. Center valve & vent not installed.
6. Center valve provision removed from the hull and splash guard installed around vent.

My boat (hull # 64) falls under #2 above. I drilled a second vent hole in the forward bump and installed positive sealing screw type plugs in both vent positions. I keep the washer and rod clean of corrosion (lubed with silicone dielectric compound) and intend to make a stainless washer/seal someday.

Don

On edit: When my ballast is full there is no sloshing and opening the center vent produces a geyser.

[restless]

Hi Don
wow.. food for thought! Didn't know about the dodgy seal rod thingy.. will check that out soonest!
200ld lost ballast? My Mrs will send you a kiss when I tell her, and that plumbing in the extra valve will give it back! I did wonder about the sloshing, even though we still use the aft bunker.
I've been wondering about putting a bigger gate o nthe transom.. does it empty out quicker under power? could be handy from time to time.. got a wakeboard stashed down there waiting for its chance!
Thanks for taking the time to set the details out.
Cheers

[Capt Capsize]

Interisting history, funny I thought my company was the only one who designed by trial and errror.

Enlarging the transom valve was the first modification I did to my 97X. Relatively easy think I used a 3' inch Valterra brand valve with a stainless steel gate. The transom is pretty thick so it took a while to grind the hole larger with a Dremel tool. Also use care in location, make sure there is room for the lock nuts on the inside the for the four 1/4 inch stainless steel bolts. I also put a spacer between the valve and the transom because the new valve mostly blocks the cockpit drain output.

Later I added a vent in the bow flotation chamber routed back to the galley with a ball valve for shutoff. Closing the valve helps keep the ballast in if the transom gate leaks a little.

Now I want to close off the bottom valve and fill in the depression in the bottom, because it has to add some drag. I am thinking of removing the valve, bolt, and washer and fiber glassing over the whole thing, and faring the bottom smooth.

[restless]

I get the impression folk leave the valve open if vented... so if the boat ever turned turtle then unless it comes up fairly quickly then she ain't gonna come back at all
So how does your ball valve work.. (unless you mean a 1/4 turn valve as opposed to an auto cistern valve?)
I was rather dissappointed to find most of my ballast had snuck out overnight when we beached once. One of the reasons I'm putting in a level sensor. Of course I never forget to close the transom valve.. ever
You reckon fairing in the mid inlet will give a bit more knotage? I would have thought that with all the turbulence of the trunk that it would be insignificant. You sound like a racer...

[magnetic]

The problem is that the water ballast system on all Mac's appears to "fail-dangerous", rather than fail-safe.

I used to have a 1993 with the vent next to the companionway/heads door; if this overflowed it spilled straight into the bilge, and a number of people put in a vertical riser pipe mod, with a large airtight valve at the top of it. This in effect created a mini-vacuum which prevented the water from slowly dribbling out of the ballast tank at speed.

I now have a 2008 and the problem with the iffy bung plug still persists - if I don't make sure that it is 100% screwed in tight, the overspill cup fills with water, notwithstanding the fact that the previous owner (Nevil) installed a very neat vent up to the anchor locker. Other than to install an electric sender unit from a fuel tank I cannot think of an elegant way to monitor the ballast which doesn't involve opening the vent and having a peek inside.

There certainly is scope for some form of ballast level indicator, particularly given the dangerous consequences of a part-filled tank; on the there is also a case for installing a daggerboard indicator, because if the line breaks at speed, the lowered daggerboard will capsize the boat in a matter of seconds. I am so concerned about this latter point that I am seriously considering inserting a removable lockpin through the daggerboard trunk in order to ensure that when it's up, it stays up (and if I install a second slot, this may also perhaps reduce the annoying clunking when the board is in the fully down position).

Does anyone have any thoughts on appropriate indicators for these two safety issues?