Standards for measuring waterline length

I am drafting rules for our neighborhood marina. We want a rule that limits the lenght of a vessel in a slip to avoid overloading the floating dock structure. We have decided to use the waterline length as the measure.

It seems simple enough to measure the waterline length if necessary with a tape, but I suspect this is easier said than done accurately - especially if there is an issue of a boat being too long to qualify.

Is there a standard for determining actual waterline length, or specified method of measurement? If so, we would like to reference it in our rule.

 

At some of our ramps we have a maximum length of boat you are allowed to launch. This seems practical as you can measure the boat prior to launching. The water line length, unless I don't understand the term, means the length of the boat measured at the watereline that you won't know until the boat is in the water. Then it will be too late. Most boats have a standard curvature at the bow so add the bit that is generally above the waterline and restrict the overall length.

 

I think you will be making a rod for your own back if you decide to use LWL. Your customers want something that is seen to be fair and equitable and you need something that is easy to check and enforce. Unfortunately, I think LWL would be neither of these.

Either go with LOA but be clear about what is and is not included (bow sprits, anchor platforms, davits, solar panel arays, anchor rollers, swim platforms, etc, etc...)

Or use some form of Hull Length (LOD), but then you still need to have a some way of dealing with boats with massive bowsprits, etc.

If your only concern is 'overloading' the docks, then displacement (total weight) would be more appropriate, but in my experience, the problem is getting people to use a big enough slip to completely contain their boat without having bits hanging over and blocking either the walkways or access channels. LWL would not solve these problems. A boat that was 25 ft LWL but that was 38ft from tip of bowsprit to tail of bumkin, would be a real nuisance in a 25ft slip.

 

Thanks - These comments are very helpful.

This is a private marina (all 40, 50 and 60 ft wet slips) that has been in service for a few years with no enforcement of boat size. As usual the developer will sell anything to anyone. Now that the owners are in control and concerned about consequenses, if we use LOA a good number of exisitng boats will be non-compliant. We are trying to balance an out-of-the-box unenforceable situation with preventing some owners from damaging the docks.

Any additional thoughts are welcome.

 

Then use LOA multiplied by some correction factor to make the rule fit the biggest of the already too large boats.

Yoke.

 

You could also make the new rules for new tenants and grandfather in the existing vessels that don't comply.

 

EXCELLENT Idea!

 

======"Either go with LOA but be clear about what is and is not included (bow sprits, anchor platforms, davits, solar panel arays, anchor rollers, swim platforms, etc, etc...)"===

Measure only bouyancy section of boat.