Is 30-degrees easy and safe?

Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
Surprised you did not ask me. For the record I as a dealer originally sold the boat and a hand in mast raising. I have experienced that previously with all water ballasted boats. With any mast raise boat, a lot will depend on weather and wave action as part of the equation as one factor to consider with any boat
@Crazy Dave Condon
Dave, how easy is it to lower the mast of a H26 to, say, 45 degrees, and then raise it, with the mainsail bent on? Does the factory system produce adequate lateral stability in small waves, or does it need modification?
 
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Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
Air draft is around 40 feet, not 44. The luff of the mainsail is 30’, and if you look at a scale drawing of the boat, you can figure out that it’s about 40’ from the waterline as drawn to the top of the mast. By my trig/math, you’d need to heel the boat 28.9 degrees to reduce the vertical aircraft to 35’.

if I can just push some ballast out with an air-mattress pump (which I already own) and lean have a crew member lean into the shrouds.
The idea of having a partially filled water ballast tank really worries me. When a water ballast tank is partially empty, the water sloshes around and actively destabilizes the boat. That’s called the “free surface effect” and it can an capsize a boat because water weight flows to the “low side”. With weight on the low side, the boat Is less stable than it would be an empty ballast tank! A partially filled water ballast tank is more dangerous than an empty tank!

If a big wave or wake were to hit you, I’m not sure what would happen.

Judy
 
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Jun 8, 2004
10,024
-na -NA Anywhere USA
@DrJudyB

With any mast raising system, you need calm water as I have seen failure with all types of systems home built and engineered systems in heavy waves and bad weathther. Only where it is safe to lower the mast will be up to the skipper. In heavy waves and bad weather, point into the wind and lower sails.

To get a more accurate from water line to top of mast. Take a measurement using a measuring tape to top of the mast measuring from deck to top of mast. Guess distance of anything at top of mast for example wind vane, antenna, etc. and add to measurement. Then measure from mast foot to water line and add that to overall measurement for distance at water line to what ever is the tallest at top of mast.

Underway, leave all the waterballast in the tank. If otherwise you are a damn fool as stabilility will be jeopardized as this applies to all manufactured water ballast boats that I either represented and the others I was on. Period!
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA


This post won’t help rgranger much, but it’s interesting. If you have the engineering know how and fabrication skills, you can build a mast raising system that works in moderate winds and sea states. (Or you can pay a boat designer/ architect to design it and then contract with somebody to fabricate and install it.).

The Dutch have been dropping masts so they can squeeze under bridges for centuries. Google Beoier sailing barge and Botterjacht. They have been used for centuries to transport cargo in the Netherlands. They generally have masts in the around 50:feet tall. The important features In their systems are a tabernacle hinge positioned well above the gooseneck, an A-frame for a lifting point, and an (optional) counter weight on the foot of the mast.

Their mast feet go below the deck ( through a trap door in the deck in front of the mast ) and are counter weighted on the bottom. They are engineered to withstand side wind and moderate wave conditions. It’s clever because no only does the counterweigh take the work out of lift the mast, it also does double duty as ballast located at the bottom of the hull.

For well thought out systems in smaller boats, Take a look at the Marshall sanderlings, and the Compac Suncat for examples of tabernacles masts with the pivot point above the gooseneck. THey don’t require removing the boom or mainsail To drop the mast. Since these are comparatively short masts, They can be easily dropped with no need for a counter weight on the foot of the mast.
 
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Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
With regard to bridge clearance. @rgranger clearly states it is a "draw bridge". The open clearance is "open" ie unlimited clearance unless your beam and or width at the spreaders is wider than the horizontal clearance on the chart. The height and horizontal clearance are listed on the charts with the draw bridge closed.

The bridge clearance is listed at height above "MHW" (Mean HIgh Water). This is not "HHW" (High HIgh Water) and that is important, especially in the Southern part of SC and Georgia. The difference be between the actual high tide and MHW can be significant since we have a tidal range of between 6 feet above datum and up to 9 feet above datum here at Beaufort (and I'd assume similar numbers in Charleston) depending on the day. Thus, on any given day the actual high tide may be significantly above the MHW number upon which the bridge clearance is published. I would be very careful on transiting that bridge closed especially if there are no height boards on the bridge.

Add to the variables are wakes from passing power boaters that come blasting by with no concern for how it bounces you. Two inches clearance is asking for trouble. You will experience a servere pucker factor when you see that power boater approach as you are starting you healed over transit especially if you only have 2 inches clearance after healing over. You'll hail him and he will either not answer or ignore you - ask me how I know! :yikes: It's your boat and your decision but think long an hard about healing over as a way to get through.
 
Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay
Our fixed bridge here displays "Minimum Clearance" in feet. So that is based on the height above the water on the highest high tides of the year.
 
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Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
I believe on NOAA charts the vertical clearance published is based on Mean High Water but I could be wrong. It might even be Mean High High Water (MHHW). The point is that it is a "mean" which is not the highest seen. With a wide range of tides the mean can be significantly less that the actual tide at that particular time.

On what chart are you referring to displaying Maximum Clearance? Maybe its semantics but I would think the words would be "minimum clearance" if referring to the clearance when at highest high water for the year? The maximum clearance would be the clearance at the lowest tide, not the highest tide. Thats really not important though as long as its understood what it means to the user. On NOAA charts (paper ones soon to be extinct) it never says maximum or minimum as far as I am aware, just "horizontal and vertical clearance" and that is based on a "mean tide" above "datum" which is established based on data sometimes as old as 20 years or more. Throw in wind driven changes in water level and things can get dicey when you don't have much clearance (for instance the Bellhaven Bridge on the ICW in North Carolina)
 
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Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
Our fixed bridge here displays "Maximum Clearance" in feet. So that is based on the height above the water on the highest high tides of the year.
@Kings Gambit - do you mean "displays" as height boards or markers on the bridge itself? In that case it's not based on datum or charts but rather on actual measurements from the bridge constructors or the USCG.
 
Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay
I believe on NOAA charts the vertical clearance published is based on Mean High Water but I could be wrong. It might even be Mean High High Water (MHHW). The point is that it is a "mean" which is not the highest seen. With a wide range of tides the mean can be significantly less that the actual tide at that particular time.

On what chart are you referring to displaying Maximum Clearance? Maybe its semantics but I would think the words would be "minimum clearance" if referring to the clearance when at highest high water for the year? The maximum clearance would be the clearance at the lowest tide, not the highest tide. Thats really not important though as long as its understood what it means to the user. On NOAA charts (paper ones soon to be extinct) it never says maximum or minimum as far as I am aware, just "horizontal and vertical clearance" and that is based on a "mean tide" above "datum" which is established based on data sometimes as old as 20 years or more. Throw in wind driven changes in water level and things can get dicey when you don't have much clearance (for instance the Bellhaven Bridge on the ICW in North Carolina)
Yes, my error. It’s “Minimum Clearance.“ (I’ve corrected.) And you are also correct about how it’s posted on the charts. However, once you arrive at the bridge and wish to go under, the sign there tells you the minimum clearance you have if, for example, arriving on a high Spring tide, etc., you’ll know if you can still pass under.
 
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Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
Here is a link to a simple diagram that explains bridge clearance. Here in southern South Carolina, we have a tidal range that averages about 8 feet but it is as low as 6 feet sometimes and as high as 10 feet a others. In essence, the "mean" is exactly that and there are many times where the actual observed high tide is significantly higher than the "mean high tide". You can see that from the barnacle line on the bridges. This is complicated by the fact that there are several bridges on the ICW around Beaufort and Hilton Head Island with no height boards. They have taken many "appurtenances" off the the top of masts and even resulted in a demasting or two to the unwary sailor.


You may need to cut and paste to get to the link.
 
Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay
Mean High Water at Los Angeles is 4.75 ft. Mean Higher-High water is 5.49 ft. But, the height of the higher high water on July 21 is 6.58 ft. So, if the chart says 47 ft vertical clearance from MHW, actual pass-under clearance might be only 45 ft 2 in at that time of the day. That would be the minimum clearance in this example.
 
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walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
The idea of having a partially filled water ballast tank really worries me. When a water ballast tank is partially empty, the water sloshes around and actively destabilizes the boat. That’s called the “free surface effect” and it can an capsize a boat because water weight flows to the “low side”. With weight on the low side, the boat Is less stable than it would be an empty ballast tank! A partially filled water ballast tank is more dangerous than an empty tank!
I capsized a Coranado 15 and a fair amount of water spilled into the hull. A couple times I got the boat upright but just a tiny bit of wind would send it back over. Got first hand experience on how incredibly destabilizing water that can move around in the hull (such as a partially filled water ballast tank) can be.

I used to lower the mast into the crutch with the main sail slugs all in place and the sail in a bag on the boom (Mac 26S). All I had to do was disconnect the boom from the mast to free more angle movement between the boom and the mast as the mast was being lowered. Pretty easy with a gin pole mast raising system and "baby stays". The baby stays allow some slop as the mast is being raised or lowered but if you just keep the crutch on the boat and lower the mast into the crutch,, it is plenty stable. After the bridge, raise the mast and connect the boom to the mast. You have keep all the mast raising stuff on the boat as well as the crutch but with the right setup, not a big deal.