GBCA Discussion Forum

Quote from: STuma on December 19, 2017, 03:29:28 PM

Quote from: WalterH on December 18, 2017, 07:57:50 PM
With all due respect I do not want to compete against boats that my boat can not compete aginst to place or win.  How about J's race against J's, there are enough of them' Then the dispacement boats can race against each other. I think that would be more fun.

I fully agree and understand. This brings my point about quantity. If we have enough boats, we can easily split the fleets as they should be. This is where I need everyone's help. I need the displacement boats to get together and agree to show up for "x" events. Unfortunately, what happens is a couple of boats show up for one event, a few different ones show up for the next event, and a couple more show up for a third event. My thought process is that the bigger racer/cruiser boats (C&Cs for example) would want a course with longer legs with some reach legs. And the end result is a race that everyone enjoys. If we have the numbers, we can group like boats.

So I agree with the displacement boats getting together and show up so we can get a class together.  It may be short notice for this race but not the rest of this series or the rest of the year.  Crew problems and boat problems can be fixed.

I'm ready to race its 3 degrees and snowing right now.  They dont get to race here all year on Lake Chautauqua.  Unless you cout Ice boats.

we are trying to figure that out because we can only do hull speed 8-9 knots and other boats can do double digits for the whole leg how can that work out in a handicap? Scott is saying in his post we need to provide enough boats to nake the classes so he can split them.  C&C race together J's race together, and so on.  So I thought the level 120 would do that but it looks like we need to be more specific.  Displacement class? and non displacement? just stirring.

found this on a boat builder forum
describes it pretty well with math and everything....Maybe it will clear it up or just muddy the wafter more?

Displacement hulls are designed to travel in the water at a typical hull speed of 1.34 *(square-root LWL) in knots. This formula applies to the distance between bow and stern wave crests. At faster speeds, wave making resistance increases exponentially because the vessel is trying to climb on top of the bow wave - meanwhile the stern is being sucked down by the dynamic forces from the "hole" created in the water as the vessel moves forward. Displacement hulls tend to have pointed bows and sterns because this form poses the least wave making resistance at "displacement" speeds. It takes a relatively small amount of power to push a displacement hull at its "hull speed."

Semi-displacement hulls tend to have wide, flat aft sections - like a New England lobster boat. These hulls are designed to partially climb on top of the bow wave and separate the transom from the stern wave. Semi-displacement speeds are usually in the area of 1.5 to 2.5 *(square-root LWL) in knots. It takes a *lot* of power to drive a hull in the semi-displacement speed range. The flat wide stern sections help to provide additional lift in the stern to partially overcome this problem.

Planing hulls are designed with straight sections aft. A typical deep-V bottom hull has the same angle to the 'V' (the same "deadrise" angle) from midship to transom. They are designed to climb completely out of the water at high speed and "hydroplane" on top of the water. At planing speeds, water is breaking cleanly from the transom and the hull is riding on its straight aft sections. The greatest resistance at planing speeds is frictional resistance. It takes more power to climb out of the water over the bow wave than it does to maintain planing speed once this is achieved. At very high planing speeds (>25kts) any change in deadrise angle in the aft sections of the hull can adversely affect performance. Hulls with a "variable deadrise" angle in the aft sections (where the angle of the 'V' decreases and flattens toward the transom) are a further modification of the semi-displacement hull form. They are more easily driven at speeds < 25kts, but at higher speeds tend to push the bow down due to the higher dynamic lift in the aft sections. Variable deadrise hulls can actually become unsafe at very high speeds >30kts because of this tendency - it is possible for the bow to dig in and cause the boat to broach at high speed.

A displacement hull can only go as fast as hull speed of the boat.  A planning hull can go faster then the displacement boat because it sits on top of the water with less wetted surface.  A foil gets the boat out of the water altogether and goes faster than a planning boat. That is not an officail answer just my version.

Hey
I am excited about a Level 120 class so who else is excited???

Level 120

I like the idea of being in the same air as the other competition.  A boat starting 45 minutes ahead of me and winning the race because the wind died is not fair at all.  That has nothing to do with racing.  All boats should be in the same air to have a fair race.  Who is level 120 and how many are racing already? 

Does Steve still have the boat?

I dont think averyone will give way unless you call it an obstruction.  Since we dropped the no luffing rule I have be luffed by boats that werent in our class.  Besides Terry when you yell just about anyone can hear you.

First of all wonderfull party at Elissa. Jazz band shrimp  everything.  Awesome race committee.  Not just saying cuz we did well.  I think the last one i went to several years ago we just stayed in the club each night.  It helped we had a car there and got around.  The jetties were very intimidating when we were trying to get out the second day.  I understand why some did not make it out- we just made it in the light air.  Had I been in a heavier boat I would not have made it out. 

I look forward to the next one
Cheers

First I love Race Q
Second we usually have someone on the bow just like a start to watch the channel and call it along with the GPS.
It is an obstruction and need to be treated as such.

Darin

Thanks for bringing us out of pen and paper.  As an old data guy I always prefer an easier way to collect data.  I don't mind entering our time individually.  Yes I fat fingered on my phone a couple times.  I will try the Race Q next time if I can remember.

Oh I forgot to mention we had ICE on the deck and we have 74 degrees this Saturday craziness like cats sleeping with dogs and everything
Where was the shrink anyway I looked for him at the party

OK
its 29 33.215 N
094 56.818 W which according to my scale on the GPS 0.2 miles from H close to the lay line

Second one we saw on the second leg sticking out of the water @ 29 35.676 N 094 56.739 W when I punched this in it was to the right of us about 20 yards starboard side heading to E close to the channel

we hit the first and missed the second one so you don't have to hit either one now.

Friday night low 32 we just might have ice for our first race!

I see 48 degrees and N10 -20 MPH for this Saturday.