Effects of racing rules on boats

On the Cross linesplan the sheerline does not terminate on the CL.

You have misinterpreted the discussion. The characteristics Mike was pontificating about have nothing to do with flare right at the stem.

Having flare in the first inch or so of the boat would have nothing to do with his claims of reserve bouyancy, CoB shift, spray management, etc. He was making a statment about the shape of the bow area. One might consider this to be from the stem back to station 3 or so...

Flared bows on plumb stem designs is probably more prevalent in powerboats than sailboats, but can be found in both. I don't know about canoes.

 

Paul B, you seem to have a bit of a chip on your shoulder. After reading this thread, I went back through some of your posts in other threads, and found you've been making a habit of talking to people like they're idiots. You know, it is possible to disagree with folks without sneering at them....you should try it sometime.

 

The lines you presented had a significant difference in their freeboard height at the bow.. nothing to do with the plumbness.. so I can claim that a concave waterline adds reserve bouyancy

Regards Teddy

 

Plumb bow also decrease pitching angle in waves (more longitudinal stability).

 

You rushed off on a very odd tangent. I didn't say anything damning plumb stems, go back and read what I said. That was entirely your interpretation. I was just defending raked stems after this

Clearly that’s not a sensible general statement.You should consider every attribute as a part of the whole vessel, never in isolation.

 

Now try it with a constant waterline!

Also consider seakeeping. All research leads to the conclusion that V-shaped hull sections forward provide the best way to achieve greater wave damping in heave and pitch. Which comes back to the whole RAO for the vessel. Again considering one aspect in isolation is poor practice.

 

Never seen one.

Just an obsevation in my offshore race sailing days... Plumb bow boats just didn't bury their noses at all as deep as angled bow boats. They didn't bang into the deep wave at all with that high acceleration as angeled bow boats. Very same observation with my own sailboats.

Terho

 

Agree, downwind in heavy air say at 13-15 knots boat speed the bow wave is smaller too.

 

Terho/Jimbo, out of curiosity, your comments seem to be more oriented towards racing, would you say the same applies to "pure" displacement hulls?

I see there is some debate over benefits of different bow shapes, Paul B already mentioned the reverse transoms originating from the IOR rules and a tendency to maximize modern boat waterline length due to mooring fees, do any other things come to mind that affect boat design in this way?

When trying to explain the difference between racers and cruisers to landlubbers I've often used an example of a camper van vs. a sports car.

Nobody in their right mind would try making a sporty camper van but for some reason we have cruiser/racer hybrids, if someone put low profile tires and a spoiler on their camper van I think we would all laugh.

I think what I'm asking is what would the the boating equivalent of low profile tires and a spoiler?

(edited to clarify)

 

I think racing developments always filter down to common use.

Racing cars into the everyday car, safety, tires, engines, oil.......

Now the low profile tires and spoiler might attribute the carbon fiber we see in construction and masts, I have an aluminum stick but a carbon spinnaker pole, it weights maybe 1/4 of aluminum being stronger and safer to handle on the pointy end.

The IOR isn't the best comparison, it was tweaked to much to lower ones rating it became a joke adding a 2" bump at a specific measurement point would lower your rating by "X". Also if you have a 100K - 300K IOR boat I don't think you care about a mooring fee. The stern over hang in late 70's on a 35' is about 30-36"

 

As Rugudaller just said it's about intended use.

Aspects of a fast sailboat hulls that make them more successful in a race don't necessarily translate well into practical cruising vessels.

Good boat design is all about optimal design for intended use. A racing design is optimized for racing, no surprise there. If you optimize the vessel for comfort, seaworthiness, durability liveability etc you'll get a different hullform.

 

Car racing has definitely contributed to both the safety and utility of everyday automobiles. The question still on the table is, has class boat racing and its accompanying rules done the same for boating?

If a boat did not have to spend time in a marina, and did not have to squeeze every microknot within the constraints of some arbitrary set of rules, what would it evolve into? The answer is, it would evolve into the maximum boat for the minimum affordable price or your everyday cruiser, insert your own idea here of what you consider to be affordable. This, of course is yet another set of constraints. Are cruisers today better than the cruisers of yesterday and if so, is it because of racing? Or is it because designers have gone ahead and harnessed modern technology and materials without much input from racing design?

 

Racing was done with very normal small cruising boats under nordic LYS or IMS-rule. So they were totally pure displacement boats. The angled bow sister ship is attached.

ps. Loved our Avance 245. Despite of the banging against the waves.

 

Be nice with our friend. we are discussing a very honorable question, and we expect honorable opinion.
You get after our friend like if you are a naval architect, so please tell us your own design input for your customers on this particular topic.
And in a nice and enjoyable way.
We are here for fun of sharing, not competing on experiences.
Ancient Kayaker is one of our most valuable member, and I learn a lot from him.
And I have a **** load of experience sailing, designing and building. But I learn every day thanks to people like AK or the other members.
So cheers
Daniel

 

What is honorable about a person with no knowledge of the subject making a declarative statement that is factually incorrect?

I did not curse the man, or question his lineage. I simply pointed out his error and provided pictoral evidence in this teaching moment.

If this sort of thing offends your delicate sensibilities then maybe you should ignore my posts.