Max fetch to mooring ball.

[Sailor 99]

I am looking at a property where it would be possible to moor a sailboat. The boat is a 50 ft monohull, weighing about 45,000 lbs. The mooring would be well sheltered from all directions but a east or north east. The fetch on these points is 20 miles. Winds here could reach 25 knots.

Is mooring here a non starter? My gut tells me yes.

Thoughts?

[GordMay]

Most will know that wave height is a function of wind speed, duration, and the distance of open water the wind blows over, i.e. fetch. Wind fetch is defined as, the unobstructed distance, that wind can travel over water, in a constant direction.
However, waves are complex, and also affected by other factors, such as water depth, and shoreline topography.

There is, also, a maximum height waves will develop, at a given fetch and wind speed, no matter how long the wind blows, and this is referred to as a fully developed sea. Waves will only increase from that height if the wind speed increases.

There’s an excellent tutorial (/w formulae) on Waves at:
"Theory and principles of waves, how they work and what causes them"
➥ Oceanography: waves

Fetch- and Depth-Limited Waves Calculator
A 20 MPH Wind, over 10 Ft Deep Water, at a Fetch of 20 Stat. Miles
should produce a Fully-Developed Significant Wave Height of 1.871 Ft., with a Period of 3.094 Seconds.
Increasing the Wind Speed to 25 Knots, would produce a Fully-Developed Significant Wave Height of 2.479 Ft., with a Period of 3.595 Sec.
➥ Fetch and Depth Limited Waves, USGS

[SailingHarmonie]

Moorings are successfully used in more exposed locations than you propose, so it's not an automatic "no". Well found boats can live on moorings under conditions that you would not want to stay on the boat for.

SO many things to consider, it is hard to know. Water depths, bottom condition? Boat's condition? Even surrounding shoreline shape, does it absorb, or reflect waves?

True of any mooring, but especially one subjected to wave action, design and maintenance (especially maintenance) is critical. Did I mention maintenance?

[Kettlewell]

Where is the location? For example, northers and nor'easters are relatively uncommon in the summer months in New England, so there are many moorings with heavy exposure to the north and east that are used for the 6-month season. If I had such a mooring I would strongly consider moving the boat somewhere else before late September northerly gales arrive. Also, is there a possibility you could move the boat elsewhere if a storm was coming?

[sailingunity]

Location is an important question.

Will there ever be strong storms? We went through a hurricane in Titusville, where there is about 2 miles of fetch in the mooring field. Fortunately we were in a slip, but about 6 boats that were on moorings were lost. The depth is only about 8 feet - but with sustained 60MPH winds, the waves were 3 feet or so, in some cases the mooring broke, in other cases it was the boat's gear (lines or cleats) that broke. The boats were not quite as big as yours, but 40-45 feet.

[Sailor 99]

Location is Lake Ontario, east end. Tonight we will get sustained 35 knots out of the west ( marine forecast ) with gusts to 45 knots (equivalent - land forecast). We can just as likely get that from the east as well.

When people come to the Great Lakes they think it is just a lake, how hard could it be? There are hundreds of old wrecks to dive on in this area, many rarely dove on because it is just too rough and people get hurt getting back on the dive boat.

That said, I visited the actual property today and it is not viable for a year round home.

That said, interesting discussion.

Thank you all.

[hpeer]

Glad to hear it worked out.

I hope you enjoy your ship.

Looks lovely.

[thinwater]

One of the most important factors is depth. If it is shoaling from deeper water to less than 15 feet near the mooring the waves will get steep and the ride will be rough. If it shoals farther out or is deep under the boat, the ride will be smoother.

If it was a factor in buying a house, I would observe it in rough weather and ask locals. If your boat is not too far, I would anchor there in blustery weather (25 knots is nothing). That would be best.

I also doubt 25 knots sustained is that actual upper limit. What is the worst sustained wind in a 10 year period? Very likely much higher, perhaps in the 40s. I would research it.