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Air draught

Posted: Sun Aug 12, 2007 1:48 pm
by bastonjock
Hi Guys
ive tried searching on this one and cant find an answer.

What is the clearance under a bridge that a mac26x can do with the mast down? the bridges on the nearest rivers to me have very low clearance plus they are tidal so what can i get under?

Matt

height

Posted: Sun Aug 12, 2007 7:36 pm
by albion
Bastonjock. If your boat is out of the water why dont you measure the height from the water line to the end of the mast at its highest point. That should give you a rough idea of the clearance you need.

Posted: Sun Aug 12, 2007 7:44 pm
by James V
The way that I fugure it, You have 6 feet headroom inside, The mast is about 3 feet higher. 10 feet (3 meter) is plenty, you may get by with 8 feet (2.5 meters ??)

The bridge height in the USA is not measured often and does change as much as 3 feet from markings.

Posted: Mon Aug 13, 2007 12:46 am
by Frank C
Depends whether you intend to have the mast at the step or mounted to the pulpit. IIRC, the height of the masthead when the base is on the pulpit is about 10 feet, but I'd want a foot more clearance to be safe.

I believe the masthead would be higher off the water when tilted aft from the mast step ... added angle-height to avoid impact with the sliding hatch.

Posted: Mon Aug 13, 2007 5:09 am
by Billy
Frank is right on an X. With the mast base on the pulpit, the masthead is about 10 feet off the ground. (Just measured,) With the mast base on the step, it is about 13-13.5 feet. (iirc) This was sitting on the trailer, now you can deduct about 2 feet for being on the water. Hope this helps.

Posted: Mon Aug 13, 2007 7:19 am
by K9Kampers
If you wanted to gain more clearance with the mast mounted on the bow pulpit, you can remove the mast crutch and lower the mast even more and support it where applicable. At this point, the issue isn't the height of the mast, but rather the hieght of your life-line stanchions on the cabin top.

Posted: Mon Aug 13, 2007 11:40 am
by bastonjock
guess ill have to go and hang off of the bridge with a measuring tape,some of the bridges have a 2.4meter clearance some others are 3.6m.


nothing is ever straight forward :(

Posted: Mon Aug 13, 2007 7:36 pm
by James V
Most of us do not go under bridges that low.

Posted: Mon Aug 13, 2007 8:14 pm
by eric3a
..

Posted: Tue Aug 14, 2007 3:03 pm
by Lovekamp
K9Kampers wrote:At this point, the issue isn't the height of the mast, but rather the hieght of your life-line stanchions on the cabin top.
With my mast off, I can fit under a 7' clearance without worry (railroad bridge on local lake); I'd worry at 6', though. Even at 7', I have to duck my head down. Mast crutch wouldn't clear at 7'.

Posted: Tue Aug 14, 2007 3:36 pm
by eric3a
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Posted: Tue Aug 14, 2007 4:10 pm
by LOUIS B HOLUB
eric3a wrote:I've go another silly suggestion (I rarely run out of those).

You can take mast off, then do that:

Image

And you will fit under any bridge.

Eric
Great description of how a Macabaago becomes a Macsubrino. Incidentally, Ive often wondered about Roger's hired help (I wonder if they speak English) ?
:D

The way I would calculate the Mac bridge clearance would simply figure the length of the mast raising tool then add the distance to the vessel black stripe at the water line. If I were touring and came to a bridge site, I would definately be using the mast raising system. (making sure the cables dont tangle in the prop).

Posted: Tue Aug 14, 2007 4:46 pm
by bastonjock
my problem is that there is no easy acess to the sea except by using the ramps down to the tidal rivers,im hoping that i can get 4meters clearance at one particular bridge.

the air draught is 2.2 meters at HW,so im hoping for another 2meters from the tide,after that its the shifting sand banks i have to deal with :D

Posted: Tue Aug 14, 2007 6:40 pm
by eric3a
..

Posted: Wed Aug 15, 2007 8:40 am
by beene
If you wanted to gain more clearance with the mast mounted on the bow pulpit, you can remove the mast crutch and lower the mast even more
Not quite that simple. On the M, if you take the mast out of the arch, the spreaders will hit the cabin top and you will bend them.

G