Square waves/ short periods

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bigpoppop

Veteran Member
Joined
Nov 19, 2015
Messages
81
Location
USA
Vessel Name
Long Time Dead
Vessel Make
Nordhavn 55
Hello- we are in our 55 nordhavn in Cartagena, Colombia. Our next leg (God willing) will be to Punta Cana DR. This will be a 4 day trip with first night at Santa Marta Marina the direct to DR. Planning to leave Sunday 4/9. Winds look very good for these waters. Problem is sea state as the was are forecast to be 5-7 feet with 5-5.5 second periods- NASTY square waves.

Question: how much can varying course to take the waves at an angle off the bow improve the ride? How much of an angle is necessary? How much can a speed reduction improve the ride?

Many thanks- wish I've had the experience to answer myself......... but I just don't!
 
Be willing to turn back.
taking the seas at 30 degrees will help, but can only do so much.
Reducing speed is imperative, at least on my boat.

But frankly, having spent too much time in such conditions, all it does is torture me for twice the time and double the cost.

Consider what you will do if you find your speed down to 3 to 4 knots.
 
Also, I have found sea state forecasts to almost always understate the conditions. Maybe because they produce an average and if the forecast is 5 to 7 feet, you hardly notice the 3 footers, but will really notice the 8 to 12 footers which will occur 15% of the time. Doesn't sound like much, but at every 6 seconds, it means in one minute, you'll see 10 waves, so you will get one to two 8 to 12 footers every minute or so.

And jsut when you thought it safe to go out, I noticed that those easterly trades blow strongley fron NE to SE and produce seas days later from those three directions while the winds are steady out of one direction.

This meant that we got a very big resultant wave every 8 minutes or so. I'm talking 3 times the size of the average waves.

The entire stretch from the Canaries to Panama was subject to these three wave trains and I have never noticed more than two anyplace else.

ANd the model forecasts are not designed to give you three swells.
 

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