What Does Bridge Height Actually Mean?

[Victoryv]

Well thanks very much! heres me feeling quite smug that I take my own boat through, and you raise the bar by going through in the dark.

 

[JanetAnne]

By the way. We measured Beccles old bridge in August. The marker boards are way out. We made it 8 inches difference! The reason we checked it was one of the boats coming to the Beccles Wooden Boat Show had failed to arrive due to insufficient clearance. Out of curiosity we went and got the boat, nosed it up to the bridge and measured the height from water to the underside. We then measured the air draft of the boat which was out by 6 inches. Combined we gained 14 inches on their original needed clearance. Through we came with plenty of space.

I did refer the marker boards to the BA at the time.

[JanetAnne]

7 hours ago, Victoryv said:

Well thanks very much! heres me feeling quite smug that I take my own boat through, and you raise the bar by going through in the dark.

 

If you go in the dark it saves all that closing your eyes stuff. Obviously finger crossing is exempt from this.

[BroadAmbition]

Hi Griff, I would be interested to know that when they give an air draft of a boat, I assume this is on it's own and when fully laden with people, fuel, water and goods so to speak, how much can this affect the air draft?

Sorry CaptainKev for the delayed reply:-

When 'They' give an airdraft I take it you mean the hire boat outfits or boat builders? - My answer to that one is simply - I don't know (Shock / horror).  I do know how we did it with 'B.A' that is measured her exactly with no room for error.  I measured her airdraft with a full diesel tank (Her diesel tank is always left full after use) and full water tanks.  There were however only two crew onboard and minimal victuals / personal gear.  The variable in this one is that sometimes she can have up to eight crew onboard (Nine once) with all their personal gear, victuals, bonded stores (strangely quite a lot most times, I wonder why?)  fishing tackle etc.  So at the time of me measuring her she was considered by me to be light in the wet stuff.  Now 'B.A' has got plenty of buoyancy, full crew etc won't make much of a difference to her plimsoll line (If she had one) with her being a fair size boat.  The smaller and lighter the boat, the more difference crew / stored up will make of course.  I could go to the trouble of taking her airdraft in various states of crew / stores, but that imho is getting to be too much of being an anorak.   So I have erred on the side of caution with regards to her actual airdraft.  If I'm in any doubt regarding bridge heights, then it's simple - I don't go for it - Don't want to do a Maurice Mynah now do I?  And besides the mark of a good skipper, is someone who never has to prove just how 'Good' they are!

Hope this helps,

Griff