H306 Mast Height From Waterline

[Robb]

I'm trying to determine the mast height from waterline on a 2005 H306 with a furling main sail. I found the owner's manual on line, and now I'm even more confused. Page 36A has a sketch of a standard sail plan boat which shows a mast height of 40.25 ft (from determined waterline). Page 36B has a sketch of an optional furling sail plan boat which shows a mast height of 44.25 ft (from determined waterline). Seems pretty clear...right? But hold on...

On the very next page, page 37, there is a Dimensions, Capacities, Etc list that documents the mast height (from waterline) as 42' 6". This is different from both sketches. Also, is there a difference between "determined waterline" terminology and "waterline"?The sketches use "determined water line" and the dimensions, capacities, etc list uses "waterline". It seems to me that the dimensions sheet should at least match one sketch or the other, right? So why doesn't it? Uggggh!

Why is this so important to me, you may ask? Well, I have a 43' bridge to get under just outside my marina. I'm interested in pursuing purchase of a 2005 Hunter 306 with a furling main sail. I need to know it will clear the bridge, and we are talking inches here. Thanks.

 

[Phil Herring]

Hi Robb,

That's not uncommon. Some of those specs were probably published before hull #1 was ever built. Specs can change during the production run but the modification may not make it into the manual. If it's a critical spec (and it sure sounds like it is) I'd run a tape measure up to the masthead if you can. Mast height from the waterline is affected by optional equipment, tank levels, gear stored aboard, and even the number of crew. In a perfect world you'd get a worst-case measurement with the boat mostly empty. But given the variance we see in specs, I wouldn't trust any published data for a dimension this critical.

 

[Robb]

Thanks Phil. I just got off the phone with Peter, an engineer at Marlow-Hunter. Super nice guy. He pretty much told me the same thing you did in your post about the drawings. His guess is that the Dimensions, Capacities, Etc list is more accurate and is for the furling mast. My plan is to measure it myself.

I am going to buy a Bosch laser measure. These are accurate to 1/16 inch. I figure if I get down beside the boat at the water line, I can take two measurements. First I'll shoot the distance from the laser measure to the side of the hull. (I'll have to add the distance from the side of the hull to the center of the mast). Second I'll rotate the laser measure up, without moving it, and shoot the tip of the mast. I'll then have the lengths of two sides of a right triangle and can figure out the third....the mast height. Voila!

(then I'll probably send a conventional tape up the halliard to confirm my findings)

 

[Benny17441]

Yes, it is a game of inches and don't forget to include in your air draft the antennas, instrument sensors and any other additional fixture protruding from the mast. NOOA charts vertical bridge clearances at Mean High Water (MHW) so by looking at the tide tables and observing the tidal range you may observe when you can or may not be able to cross the bridge. There is only one way to get your air draft and that is to measure it. Get someone up the mast with a loose line and mark from the top of the mast + fixtures to the base of the mast on deck. Then at your leisure you can use a measuring tape to get the length of the spar by measuring the distance between the marks on the line. Then lean the boat against a pylon and shoot a horizontal line from the base of the spar to the pylon and mark. Then measure from the waterline to the mark and add both measurements which hopefully will be under 43'. Consider the boat's load at the time of measurements, persons aboard , fuel and water. Also look around the marina and talk with sailors that may have a similar air draft and see what their experience actually is with clearing the bridge. Find out if they have to plan their departures and arrivals around the tides and how often may they be inconvenienced. It might prove to be a non issue or a clear indicator that you need more clearance. You may stipulate in the contract the maximum air draft you are willing to accept as per survey and indicate to the surveyor that he must be willing to provide such measurement in his report. It's Florida so we are kind of used to sail around the tides.

 

[John T1594]

Be careful about what is charted on the NOAA nautical charts regarding bridge clearance. We have two bridges in New Jeresy that are charted at 60' of vertical clearance at MHW but when you get there at Low Tide the clearance tide boards show between 56' to 57'. I can barely make it under with my 56' mast (Dimensions) on my H340 with inches to spare. You may have to go under the bridge with a laser range finder to be certain of the clearance.

 

[Robb]

Great stuff guys. I'm going to measure tomorrow. I like the pylon idea Benny. Who knew measuring a sailboat mast would be rocket science? Haha.

 

[Robb]

The verdict: The owner and I measured the mast height today. I first tried to use my new laser measure but the beam was not strong enough to see at the top of the mast. I lost the laser beam about 3/4 of the way up the mast. $100 wasted on a fancy laser measure. So, we marked a spot on a pylon that was perpendicular to the base of the mast, and then measured down the pylon to the water. This was 5' 5". Then we ran a line up the halliard and marked the other end of the line where it contacted the base of the mast. We then took the line down, laid it out on the dock and measured it. That measurement was 37' 6". We then added a foot to account for the mast head light and wind duffer. Total mast height from actual water line we figured at 43' 11". I estimate adding another foot or so on top of this to include the VHF whip antenna. (45')

Bottom line....this boat is too tall for me. Too bad because this is a super nice boat at a great price. If you know anyone looking for a boat, this was a 2005 H-306 located in Pensacola. Interior looks brand new, no kidding. Asking price is $35,900. I've done tons of research and this is a great deal. PM me for more details if interested.

Thanks for everyone's input, much appreciated. Merry Christmas!