MacGregorSailors.com

ALX357 wrote:trying a test board first using the bracket and line without making a trailer mod would be really difficult. You'd have to be in shallow water, deep enough to float the boat with board "down" and shallow enough to have standing footing to manage the swap, and the lungs to work underwater several minutes at a time, or SCUBA gear, or an air hose etc.

If you had your Mac on a boat lift, you could put in a CB going under it by standing on a dinghy or raft. Then lower the boat and test out each new board pretty easily.

hadn't thought of that.... haven't ever had access to a lift, but that would make it easier if you had access for a day and were close to a good spot for sailing test runs.

Greg,
you're right, making a test board would be the pudding. I wonder if there is anyone on the board who could make a mathematical prediction of how a 5'7" x 12" keel/CB would perform (horizontal position).

The X CB is not very good in several aspects which have been mentioned before. If the boat's performance could be improved with a CB mod, that would be a feather in our cap.

Here's another possible CB design:
Make two CBs that fit into the trunk.
Each CB can be deployed individually.
When the are both down they can be at different attitudes so that comined they can resist more water. (like one stacked on the other)

You might be surprised how much clearance you have when launching. On the typical ramps we launch on as you back the boat in it floats up off the trailer quite a bit. I would guess there is close to 12" clearance from the bottom of the boat to the trailer crossbar. You could always back in a bit deeper than normal for the test.

One of our launches this summer illustrated this nicely. We were in a rush to launch for a day trip. Once at the head of the line we quickly pulled around and backed in. Something didn't seem right, the boat was suddenly angled toward the dock. Drifting, wierd. I seem to be back as far as normal but the fenders just aren't going under the surface. Oh Crap, we didn't remove the rear trailer strap. The entire trailer was lifted well off the ramp floating along with the boat. Luckily no one seemed to notice our goof. We quickly pulled back up the ramp, removed the strap, and launched as normal.

I don't know about the effectiveness of the board in this horizontal position, but my gut feeling is it will make sailing performance worse, not better.

I do however think a good addition to an X board would be a very thin addition that extends from the leading edge. This is not for any additional sailing gain when the board is down, but to serve as a skeg when under power with the board up. A simple flat section that generates no lift at higher power speeds, but enhances directional stability would go a long way toward the boats constant yawing back and forth. I envision something that sticks 2-3" below the hull when the boat is up. It would be about 18" long. Made of 1/4" aluminum plate welded to a bracket that simply screws to the front of the cetnterboard up near the pivot point. I don't think this would have much impact on sailing performance with the board down and might go a long way toward making the boat behave better under power. The 3" extention below the hull shouldn't pose any problems with the trailer on a normal launch ramp.

Duane,
I like your idea. I wanted to put a little motoring skeg on mine almost from day 1, but couldn't think of a good way.
That sounds like a very easy way to do it and still preserve trailerability.

craiglaforce wrote: ↑Thu Dec 15, 2005 4:52 am Duane,
I like your idea. I wanted to put a little motoring skeg on mine almost from day 1, but couldn't think of a good way.
That sounds like a very easy way to do it and still preserve trailerability.

Yes, this is an old thread but does have an interesting aspect that has recurred…. Making a limited depth skeg blade for a Mac26X.

One thought came to mind when we were replacing out swing keel retrieval line this past Spring.
Makes a second pivot hole in the top of the keel about 2 inches higher than the existing pivot hole.
Then add a 2” foam spacer to the aft end of the swing keel trunk,
That way when the keel is pulled up it will be protruding 2” from the trunk parallel to the hull bottom.

To adapt the trailer for the required “notch” is a relatively minor affair.
If one has a trailer with longitudinal parallel bunks it is a non event as there is typically nothing 2 feet to either side of centerline.

Might give this a try after we haul out for the winter…..

Over Easy

I just lower the keel slightly when I want a little bit of "skeg". The rope holds it up just fine and the keel still fold up completely into the hull when I want to beach it. Your way would give a longer "skeg" but there is more chance of damaging the keel on the trailer or bottom.

Hi Be Free!

Yes, your right. Dropping the keel down a little bit does add stability and still allows it to “bounce” back up out of the way. It is what we have appreciated several time about the Mac26X swing keel.

We have also noticed that when motoring at higher speeds (not that that has happened much with our engine until recently after we solved several impediments ) that the keel tends to get pushed up as speed increases.

With the keel fully retracted the handling at speed tends to ‘slide’ about. Especially at the transition to getting up on plane.

With the keel extended a small amount via the lift rope the handling is better with less slip initially but than benefit tends to diminish as speed increases and water pressure pushes the keel back into the trunk as evidenced by the keel lift rope developing slack.

The idea of a some what more stable skegg is interesting, especially if it is not requiring extensive modifications or permanently or irreversibly altering hardware.

There appears there is sufficient room currently to accommodate the proposed 2” hole position on the swing keel and in the keel trunk space. The 2” tall foam insert at the rear of the trunk should stay in place (TBD by testing) while the boat is at motoring speeds as it is fully captured. During sailing operations the side friction should be sufficient to keep it in place.

Several people appear to have made permanently mounted skeggs to the bottom of tier hulls or to have permanently altered their keels to add leading edge extensions.

Figured that given my longitudinally oriented bunks and the space between then it is something worth considering. Obviously beaching and grounding issues are to be avoided with this.

We appreciate your perspective and it is a valid one.
Taking that into account we might simplify the process and just insert the foam piece into the back end of the keel trunk (to keep it from ‘riding up’) to see how it works! That avoids needing the extra hole at the pivot AND leaves the keel at a slight angle to avoid a potential hard contact at the ‘front end’ of the keel!
Thank you!

Best Regards,
Over Easy

ONE TIME (and only one time!), I forgot to raise my centerboard when I switched to engine power. The boat is very hard to control and wants to heel as the speed increases. The same would happen if your board came down accidentally at high speed. As you have noted, the forward speed tends to push the board back into the trunk but at some point it would drop and you will be quickly faced with a drastic change in the way the boat handles. I only use the "skeg" trick to get a little more stability at low speed. I've just learned to handle the boat as it goes through the transition phase. I remember a post years ago from an owner who added extra weight to his keel. I don't remember if it dropped at speed or if he was intentionally running it with the board down but I recall that he ended up losing the board completely.

Hi Be Free

Thanks for the heads-up about motoring with the keel down.
Having a keel fully deployed while motoring would definitely change the pivot dynamics..
I could just see myself trying to figure that out until I stumbled upon the loose keel line,

We might give this a try though with the limited protrusion keel limited to about two inches when we are up North and regularly trailer launching so I can easily get to the underside to control the setting of the keel. It will be in September at the earliest the way the schedule looks.

A cautious approach will be the order of the day.

Best Regards,
Over Easy