My newest project

olaf hart

Super Anarchist
Olaf:

That's a bit of a tough one. Might depend on just how you define" comfortable cruisers" But my guess would be a D/L over 140 and under 180, maybe as high as 200 if you want volume and stability. I think if you get the D/L under 130 you may have bulb provided stability but you still will not have a comfy ride. For the rig where you have some breeze I'd say nothing over 17.5 in a mast head rig and nothing over 18.50 for a frac rig.

There are a lot of variables but I think those numbers are relatively representative.
That's really interesting, I would think you would be the most experienced person around to answer that question from the "pattern recognition" angle.

According to sailboatdata, the Adams 13 has a SA/D of 29 and Disp/Length of 96.

The Radford is lighter and has more sail, can't find published figures but it will be even more extreme.

A lot of folks have cruised a long way in the Adams ,including some close friends who don't have any issues with comfort, just note it is very tender upwind.

Do you think beam becomes a variable at this level? The Adams only has 10' beam.

 

Rantifarian

Rantifarian
Would waterplane area or PPI immersion be a more useful measure than bmax for describing a boats motion when compared with displacement? Beam will equate the hullshape of a pinched arse ior and cheese wedge of equivalent beam as the same motion, waterplane recognises at least some difference.

I wonder if anyone has ever bothered comparing a moment of area of waterplane about the centre of buoyancy and looked at correlation to sailing comfort. Probably more work than the accuracy would justify

 

Bob Perry

Super Anarchist
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Olaf:

I think you live in an area that has been ahead of the US in investigating the advantages of light boats. I'd say New Zealand would be in a similar situation. I'd have to add some factor to reduce D/L's to comply with your range. D/L's under 100 are for race boats in the US. It was not so long ago when Seattle Yacht Club established for rating purposes "ULDB's" as starting at D/L 150. Shows you how time changes things. Today 150 would be considered "medium" and just maybe "medium light".

An SA/D of 29 like the Adams has is today in race boat range. Maybe not the newest sport boats which are pretty extreme in sail area but certainly top level club racers. That's a lot of rig for a cruising boat. It would take a skilled sailor to keep that boat under comfortable control. As you say it's "very tender upwind". Of course it with that kind of horsepower per pound.

" Back on the rail dear!"

Maybe we have a different view of "comfortable".

Ranti:

Maybe. I'll have to think on it. Remember, as I said, if you have two 40'ers with a 10,000 lb. displacement difference, waterplane will be quite close. It does not reflect overall displ at all. I would take a wild ass guess and say the range of waterplane areas for boats that share similar DWl and BWL numbers would be within 10% of overall waterplane area.

In past years when I would have some eager high school kid in the office for the summer this is the type of job I'd give to him, compiling comparative numbers.

 

Rantifarian

Rantifarian
I was thinking waterplane would be lower for deeper hulled boats with plenty of deadrise, low PPI but lots of inches to make up the lbs. Not often you see a waterplane published with a design, so I nfi about the real numbers.

You are probably right about the spread of numbers, until you get to more extreme corners like the Adams hulls vs a pogo.

Great learning tool for a student, gets them nice and intimate with the details of a wide range of hulls, and still has a purpose. I need to find a way to include yacht design into a subject at school

 

Panope

Super Anarchist
1,446
609
Port Townsend, WA
Bob, the new gaffer design is great. Right up my alley with the pilot house, traditional styling and modern materials.

As with all your projects, I look forward to the continued development and eventual building of the boat.

Cheers,

Steve

 

SemiSalt

Super Anarchist
7,752
269
WLIS
Would waterplane area or PPI immersion be a more useful measure than bmax for describing a boats motion when compared with displacement? Beam will equate the hullshape of a pinched arse ior and cheese wedge of equivalent beam as the same motion, waterplane recognises at least some difference.

I wonder if anyone has ever bothered comparing a moment of area of waterplane about the centre of buoyancy and looked at correlation to sailing comfort. Probably more work than the accuracy would justify
There were some notions at one time about "anti-pitching" characteristics. As I understood it, the thought was that the bow and stern each have an inherent frequency of pitch, basically, how fast they would rise if depressed. If the two are the same, they reinforce each other and the boat pitches more heavily than if they are different. Of course, the weight and CoG location of the mast and keel have a huge effect on pitch.

Some designers have tried to tune their boats for the wave action they expect, e.g. 12 Meters in Newport, so the period of the waves doesn't reinforce pitching.

 

robalex117

Super Anarchist
How big is that alternator? Anybody know the manufacturer?

Visited the Carbon Cutters this morning. That Jim Betts runs a very impressive shop. Well laid out and well organized. Lots of talent in that building especially Jim, who can be pressed into service for just about anything boat building when there is a need. Here he is machining some custom bearings for the cutters:
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Here is the shop floor with numerous activities and projects of Cutter pieces coming together:
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Here is the amazing alternator set up:
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And the bowsprit mockup:
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Presuming Ed

Super Anarchist
11,019
180
London, UK
There is an argument about that. I believe that definition came from the CCA rule, who needed a definition in writing more that "big mizzen (/driving sail) = ketch. Small mizzen (/balancing sail) = yawl."

Plenty of things like canoe yawls with a small mizzen, but aft rudder.

 

Panoramix

Super Anarchist
Olaf:

That's a bit of a tough one. Might depend on just how you define" comfortable cruisers" But my guess would be a D/L over 140 and under 180, maybe as high as 200 if you want volume and stability. I think if you get the D/L under 130 you may have bulb provided stability but you still will not have a comfy ride. For the rig where you have some breeze I'd say nothing over 17.5 in a mast head rig and nothing over 18.50 for a frac rig.

There are a lot of variables but I think those numbers are relatively representative.
That's really interesting, I would think you would be the most experienced person around to answer that question from the "pattern recognition" angle.

According to sailboatdata, the Adams 13 has a SA/D of 29 and Disp/Length of 96.

The Radford is lighter and has more sail, can't find published figures but it will be even more extreme.

A lot of folks have cruised a long way in the Adams ,including some close friends who don't have any issues with comfort, just note it is very tender upwind.

Do you think beam becomes a variable at this level? The Adams only has 10' beam.
I think that it is also very much dependant of the shape of the forward part of the boat. I remember doing a bit of cruising on a First class 12 which was a one tonner and to my surprise the boat had a very comfortable motion at sea. IME light boats with flattish sections forwart can be a nightmare and really not suitable for cruising.

 
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Presuming Ed

Super Anarchist
11,019
180
London, UK
Bob Perry said:
Saturday afternoon and apparently Jody is bored. Not very Euro is it?
Interesting. Why take the main peak halyard to the end of the yard like that?
Also never seen peak and throat halyards on a lug. Normally just hook he yard onto a traveller on the mast unless sails are really quite large. Out of interest, why go with 2 halyards?

o80722_spiritofmystery_003.jpg


 
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SemiSalt

Super Anarchist
7,752
269
WLIS
Moccasin_2.jpg


Bolger boat. Standing lug with spritsail boom. The difference in effect between this and the balanced lug is pretty minor, but the yard and sprit boom don't project as far ahead of the mizzen mast. That might or might not be important depending on rest of the layout. Note the mast height above the yard both in the picture and in the one above. I don't know the reasoning about this for sure, but the section of halyard between the yard and the sheave has to allow the yard to swing. I can see that wear, tear, and chafe could be a problem if it was too short.

 

Bob Perry

Super Anarchist
31,915
1,228
Thanks Semi:

I looked at a lot of examples before drawing my "loafing lug". Still not aware of the differences in the minor variations. I can see the advantage of having more mast height. I wish I had some lug sailing experience. I wish I could call Phil.

Not sure if I'll use the single halyard gaff arrangement. It did have limitations you don't get with throat and peak halyards. My current inclination is to offer suggestions but leave the final rig details to the clint's choice. He's far from a newbie and he as, as do I, plenty of gaff rigged boat experience. He the one who will have to live with it. It should be the way he wants it.

Could be there would some problems with the single halyard rig on this boat as due to the higher gaff angle compared to the rather ftat gaff angle of JAKATAN. I like the extra shape control of two halyards.

Doesn't look like a peak halyard is required. That's one less line.

Not going to get into "is it a ketch or a yawl?" debate. You can call it anything you like. In light of the movement of rudders in the last 50 years I feel strongly that the old definitions don't work anymore. I tend to go with P. Ed's approach, i.e. big mizzen =ketch, small mizzen = yawl. My boat is probably a yawl. I'll call it Arnold.



 
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savoir

Super Anarchist
4,907
195
I'm voting Arnold. For those who want something different.

Horshack.jpg

 
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Bob Perry

Super Anarchist
31,915
1,228
BTW:

My client , the man in the moon, is reading this thread and enjoying it very much. I got two emails from him this morning and he is very happy with the progress of the design. He's still up in the air on a couple of items but at this stage everything can change.

Client says, "It is a phenomenally good looking boat".

That's what I want to hear.

Jody and I can walk around with smiles on our faces today.

 
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