| How important is relative boat weight? #138025 03/28/08 09:58 AM 03/28/08 09:58 AM |
Joined: Nov 2002 Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... Mary OP
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Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... | Having been in one-design classes where boat weight difference can be up to 30+ pounds, I am wondering how important this is to people.
Also, something I have observed is that as fiberglass boats get older, they tend to get heavier (from absorbing water). And their original sails seem to get fuller (blown out). That combination seems to work well -- heavier boat, fuller sails.
But then the sailor decides he wants to get new sails. The new sails are flatter and sleeker, but they don't have the power needed to propel the heavier boat.
What do you think about all this? Especially, whether you think it is a big deal if your boat is heavier than somebody else's boat in the same one-design class -- or formula class, for that matter.
Last edited by Mary; 03/28/08 10:15 AM.
| | | Re: How important is relative boat weight?
[Re: Mary]
#138027 03/28/08 11:22 AM 03/28/08 11:22 AM |
Joined: Sep 2007 Posts: 571 Hamburg Smiths_Cat
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Posts: 571 Hamburg | Hi Mary,
good idea to bring this topic to the general forum.
The impact of weight on performance is much smaller than many people think. Why? The first reason is, because heavy weight hurts only in light winds. As soon as you have to de-power the sails, the extra weight gives you more righting moment and you can use more pressure in the sails and hence you are faster (up wind). Down wind you are slighly slower in any wind conditions. But you win a race on the up wind leg anyway. (okay I have to say: I assume that the weight difference is in the hulls, not in the rig). The second reason: If your 150kg boat is 5% over weight, then your total weight (assuming 150kg crew) is just 2.5% over weight. Somebody may play with texel or schrs calculators to find out, how many percent performance are equal to 2.5% more total weight. I guess below 1%. How big is the skill difference between sailors? Something over 10%, I guess.
Common understanding says heavy weights win in strong winds and light weights win in light winds. At least that is my experience in any sailing boat.
Another common understanding is: The reason why we lose races is because our boat is too heavy. The reason why we win is because of our skill of course. That's the reason why some people concentrate so much on weight. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
As long as you don't sail races only at light winds I would not care about these weight differences.
The impact of weight on boat handling at the beach however is another story. On our beach with soft sand and steep slope, we removed even the rudders of our Dart (which is only 140kg). Maybe we are too weak... Last comment on weight: Every kilogram you can save in the rig is worth doing it, because it helps to righten the boat after capsizing.
About the new and sleeker sails, I don't know... I think that even a new sail has more camber than required. You have to pull it flat anyway. I have never had the problem of a too flat sail, but I know only a few boats of course.
Cheers,
Klaus | | | Re: How important is relative boat weight?
[Re: Will_R]
#138028 03/28/08 11:25 AM 03/28/08 11:25 AM |
Joined: Jul 2001 Posts: 1,200 Vancouver, BC Tornado
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Posts: 1,200 Vancouver, BC | On the contrary, most modern boats do have cored hulls. And yes, all polyester/epoxy materials absorb water (they are hygroscopic) and gain weight. The boat doesn't even need to be in the water to gain weight...moisture is drawn out of the air and over time, it adds up (increase is something like 1-3% of the weight of the resin). Only way to really combat this is to put in the boat in an arid climate for weeks/months to dry out. I think you have a couple of issues to deal with on this question. Construction methods have changed a bit and now "newer" boats don't gain weight as badly as the older boats. The reason being is the core or lack of core. A H14/16/18 has a foam core that absorbs water and that's where the weight comes in. H20's, I20's, 6.0's and most the other newer designs don't have cored hulls and don't absorb as much water. I can say that my old H20 was still under class weight even as a 10 year old boat.
The issue with those boats becomes stiffness and that can make a difference.
To those that care enough to change hardware to remove weight, yes it matters and is important. Relative speed difference? Typically it's a game of inches out front but good sailing will overcome 5-10 lbs or more of boat weight.
Mike Dobbs Tornado CAN 99 "Full Tilt"
| | | Re: How important is relative boat weight?
[Re: Mary]
#138030 03/28/08 12:54 PM 03/28/08 12:54 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | Having been in one-design classes where boat weight difference can be up to 30+ pounds, I am wondering how important this is to people.
Also, something I have observed is that as fiberglass boats get older, they tend to get heavier (from absorbing water). And their original sails seem to get fuller (blown out). That combination seems to work well -- heavier boat, fuller sails.
But then the sailor decides he wants to get new sails. The new sails are flatter and sleeker, but they don't have the power needed to propel the heavier boat.
What do you think about all this? Especially, whether you think it is a big deal if your boat is heavier than somebody else's boat in the same one-design class -- or formula class, for that matter. Are you kidding? Boat weight makes a HUGE performance difference! (in your head)
Jake Kohl | | | Re: How important is relative boat weight?
[Re: Mary]
#138035 03/28/08 03:39 PM 03/28/08 03:39 PM |
Joined: Sep 2005 Posts: 1,187 38.912, -95.37 _flatlander_
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Posts: 1,187 38.912, -95.37 | Especially, whether you think it is a big deal if your boat is heavier than somebody else's boat in the same one-design class -- or formula class, for that matter. We race one of, if not, the heaviest boat in our class. The difference in weights, from lightest to heaviest, is minor (3.5%). Our crew weight is 20 to 30 pounds over minimum. We've had our best finishes in less than 10 knots of wind. This boat seems to be very negligable of crew weight. For us (weekend warriors) no big deal.
John H16, H14
| | | Re: How important is relative boat weight?
[Re: _flatlander_]
#138037 03/28/08 05:26 PM 03/28/08 05:26 PM |
Joined: Jun 2001 Posts: 1,459 Annapolis,MD Keith
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Posts: 1,459 Annapolis,MD | Especially, whether you think it is a big deal if your boat is heavier than somebody else's boat in the same one-design class -- or formula class, for that matter. We race one of, if not, the heaviest boat in our class. The difference in weights, from lightest to heaviest, is minor (3.5%). Our crew weight is 20 to 30 pounds over minimum. We've had our best finishes in less than 10 knots of wind. This boat seems to be very negligable of crew weight. For us (weekend warriors) no big deal. In my experience, boat/crew weight doesn't hurt performance in the light stuff and heavy stuff. Heavy weight hurts you worse in the medium conditions, where lighter crews can begin to fly a hull easier and earlier while you're still trying to power up. | | | Re: How important is relative boat weight?
[Re: Keith]
#138038 03/28/08 05:48 PM 03/28/08 05:48 PM | Anonymous
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Unregistered | Weight is major and to state otherwise is deluding yourself.
Mary, your assumption that the old sails better suit the old boat also has issues but lets keep it to one argument at a time.
A couple of case studies.
2 boats get perfect starts on a perfectly laid line. Assuming both boats are travelling at the same slowish speed when they cross the line the boat that gets to full speed first will have a definite advantage. If its the windward boat it will overhaul and then gas the leeward. If its the leeward boat its foils will generate more lift sooner (due to its increased speed) and it will pull ahead and then lee bow the windward boat. Either way the light boat wins.
You go around the top mark a boat length apart. If the lead boat is lighter it will accelerate away and the aft boat won't get a chance to attack. If the aft boat is lighter it will make up ground on the maneuver and be sitting in an attacking position when the two boats reach full speed.
If you do some quick back of an envelope calcs you'll see that without even considering the added drag while at speed at boat+crew that is 10% heavier will loose about 1/2 a boat length on every maneuver. | | | Re: How important is relative boat weight?
[Re: ]
#138039 03/28/08 07:20 PM 03/28/08 07:20 PM |
Joined: Jun 2001 Posts: 1,459 Annapolis,MD Keith
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Posts: 1,459 Annapolis,MD | Weight is major and to state otherwise is deluding yourself.
I didn't say weight didn't matter, or wasn't "major". My statement was that in light air weight doesn't hurt as much as people think. I'll stand by that. I said extra weight hurts more in medium conditions, and I'll stand by that as well. I don't believe extra weight is automatically helpful in heavy air, but that's more boat dependent. So we're almost in agreement. I'll say that every Hobie I've sailed/raced (14, 18, 20) wanted lighter crew (and boat) even in heavy conditions to sail better. The only time that being heavy didn't hurt was in light air. The Nacras I've sailed and raced (5.8, 6.0, 20) haven't minded the extra weight as much in heavy conditions, in some cases it's helpful. But again, where it hurts most is in medium conditions, not the light stuff. In light air so many other things matter. And, for almost everytime I've seen a lighter boat/crew out accelerate me as a heavier crew/boat I've coasted through the next lull as they slowed earlier. Actually keeping boats moving though maneuvers is key, and reduces the acceleration difference coming out - most people don't do it well in light air. If you're smooth a heavier boat can keep momentum better through a light air tack or jibe. That's been my experience, spoken as somebody who has sailed ~400lbs of crew weight on a regular basis. If that makes me deluded than so be it!
Last edited by Keith; 03/28/08 07:22 PM.
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[Re: Cheshirecatman]
#138040 03/28/08 07:34 PM 03/28/08 07:34 PM |
Joined: Apr 2007 Posts: 148 Cutler Bay, Florida Bajan_Bum
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Posts: 148 Cutler Bay, Florida | Don't forget that each extra lb. of weight in the boat/crew is another lb. of water that water that has to be moved out of the way for each boat length travelled, plus additional skin friction/drag. Also within the same hull design a lighter displacement boat will generally turn more easily. The heavier boat/crews have to generate more power from the rig and have higher sheet loads.
Cheshirecatman Here's my reason to lose a few pounds. | | | Re: How important is relative boat weight?
[Re: Bajan_Bum]
#138041 03/28/08 07:59 PM 03/28/08 07:59 PM |
Joined: Apr 2003 Posts: 1,669 Melbourne, Australia Tornado_ALIVE
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Posts: 1,669 Melbourne, Australia | From the F16 Forum Make a viper weigh 107kg and it WILL be faster than the std boat. What do you mean by "standard boat"? This is a formula class. As far as the Viper itself, the designer/builder says that if it were 18 kg lighter, it would be faster by only 30 seconds per hour. In a big fleet regatta an extra 18 kg will set you back 30 seconds, possibly more on each downwind leg alone. More so if your crew weight is not down to optimum weight. You will be forced to run hotter angles then the lighter boats and they will just suck down inside you (if they are behind you) and gybe well in front of you. The boats in front will just stretch their lead further..... Hence it will cost you many positions..... Forget time. 30 seconds can be turned into 2 min 30 seconds over the course of a race within a big fleet as each boat passes you and feeding you gas. I have raced my F18 carrying an extra 18kg of crew weight onboard and watched this happen many times. Then when I am sailing at min weight, the disadvantage is gone and you are doing likewise to the heavier boats. Upwind also, the heavy boat will not accelerate off the line like the lighter boats (The most important part of the race) and it will not be able to sail with as much height or speed. | | | Re: How important is relative boat weight?
[Re: Tornado_ALIVE]
#138043 03/28/08 08:19 PM 03/28/08 08:19 PM |
Joined: Dec 2005 Posts: 1,121 Eastern NC, USA tshan
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Posts: 1,121 Eastern NC, USA | I have raced my F18 carrying an extra 18kg of crew weight onboard and watched this happen many times. Then when I am sailing at min weight, the disadvantage is gone and you are doing likewise to the heavier boats. Just for arguments sake.... The quote above references 2 crew weights, which (to me) may mean two dfferent crew members. Could the performance difference you experience be related to having different crew onboard? Certainly crew work would reflect on your ability to get around the course/manuever/etc. Just asking, as your assertation seems to be fairly general and COULD be misleading to the exact cause of the decreased performance. No disrespect to the crews involved, of course. EDIT: BTW I try to keep my boat down to minimum. I think it is challenging and it gives a mental edge. I just wanted to point out that there MAY be an issue with the general logic of the above-mentioned quote. End Lawyer-speak.
Last edited by tshan; 03/28/08 08:23 PM.
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[Re: Keith]
#138044 03/28/08 08:58 PM 03/28/08 08:58 PM | Anonymous
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Unregistered | Sorry mate,
I wasn't addressing you in particluar, your's just happened to be the last post. | | |
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