Hunter 45 Center Displacement Length Ratio

[sailorboy1]

Originally Posted by patriot17

From the book Annapolis Seamanship, boats with a displacement length ratio should be over 325 for a heavy cruiser. Anything in between 200-325 is a moderate displacement cruiser.

You are reading old info about old boats and trying to apply it to newer designs.

Most newer designs carry their length a lot further and have a longer LWL, so they end up with lower a DLR.

An example is that my last Cal-39 have a DLR of 245 and a displacement of 17,500 lbs, this would be a mid displacement boat. My current boat is only a few feet longer, has a DLR of 166 and displacement of 20,200 lbs, and would be a light boat back in the day of your book. Which do you think is going to be more comfortable?

[Gerrycooper56]

Friends cruised a 2003 Hunter 45 cc for 2 years from Florida to Trinidad, Bonaire and back to Fl. No boat model specific problems


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[Aguatherapy]

Hi, we have a 45cc for sale, 2006 model but bought her in 2007. We crossed the Atlantic in her. She has a lead keel and a 7'2" draft which helps in those kind of seas. Unfortunate you are on the West coast we are on the East in Fort Lauderdale. She is perfect for full time living aboard and is turn key. You will not find a better equipped boat anywhere. Take a look in boats for sale I listed her yesterday. We have a broker but I'm also trying to sell ourselves too.

Agua Therapy is not exactly a "normal Hunter" everyone says she looks like new. We did things th at most wouldn't do like replace the standard fridge freezer for a more efficient one. Things like the combination microwave oven convection and grill are not normal things on a hunter. Take a look to see what you think. She's a proven boat, I have no idea how many thousands of pounds/dollars we have spent on extras. Only reason we are selling is we want to do the ICW and the "Man Friday" islands in the Bahamas and are going to buying a trawler.

BYE

[Aguatherapy]

Sorry should have said she's no slowcoach either, but she's never been raced.
Always kept us very safe in big seas and is very comfortable. We changed the TV and the sound system, AIS class B so even that is not a normal one.

I could go on but if you do want more info let me know.
Thanks

[DaveC]

The old ratio system still works for modern boats. The problem is that most modern boats are made to be fast, sleek looking, and cheap to build. All this equates to flat undersides with a bolt on keel, which generally yields a low DLR. Compare that boat with a similar sized boat with a large DLR and you'll find the boat with the higher DLR will generally have a more comfortable motion at sea when there is decent wave action.

DLR is simply a description of how much of a boat of a given LWL is "in" the water rather than "on" the water. It's based on the boat's LWL and displacement. A heavier boat which is has the same LWL as a lighter boat will have much more boat below the waterline. This means that it will get thrown around less by the seas and wind than a lighter boat of the same LWL, which basically floats around like a cork with a comparatively flat underside and will get tipped and turned easily with the wave action as compared to the heavier one with a more rounded and deeper hull (notice I didn't say keel). This results in a less comfortable ride in moderate+ conditions than a deeper, rounder hull.

The heavier displacement doesn't necessarily mean slower either because that comes down to sail area vs displacement. For the same sail area and displacement then yes it would be slower in light winds due to more underwater friction.