| Re: Flex
[Re: PTP]
#111343 07/11/07 04:00 AM 07/11/07 04:00 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe |
Try tightening your beam bolts ones more.
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Flex
[Re: gary145]
#111346 07/12/07 02:19 AM 07/12/07 02:19 AM |
Joined: May 2006 Posts: 954 Mumbles Y.C Wales U.K Mark P
old hand
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old hand
Joined: May 2006
Posts: 954 Mumbles Y.C Wales U.K | The flex between hulls should be no more than the thickness of Wouter's little finger according to one of his previous posts. For such a scientific man it is very amusing that he uses his digits for measuring and probably counting <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> MP*MULTIHULLS | | | Re: Flex
[Re: Mark P]
#111347 07/12/07 03:45 AM 07/12/07 03:45 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | The flex between hulls should be no more than the thickness of Wouter's little finger according to one of his previous posts.
This applies ONLY to one specific F16 design made by one specific builder. For such a scientific man it is very amusing that he uses his digits for measuring and probably counting
This coming from a guy belonging to a people who still measure all distances in the length of a dead kings foot or thumb (inch). <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Wouter
Last edited by Wouter; 07/12/07 04:19 AM.
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Flex
[Re: PTP]
#111348 07/12/07 04:02 AM 07/12/07 04:02 AM | Anonymous
Unregistered
| Anonymous
Unregistered | If you are only get a inch of movement one bow to the other you have nothing to worry about. <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" /> Picked up the bow of a Hobie 16 lately <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />.
"Altered" moved inches, didn't slow it down much <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />. | | | Re: Flex
[Re: PTP]
#111349 07/12/07 04:31 AM 07/12/07 04:31 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Method :
Demast the boat, so you have a bare platform.
Lay the platform up on two sawhorses or chairs so that the rearbeam is aligned perfectly horizontal.
Lift one bow and put that on a sawhorse or chair as well. Then use a rod or plank to bring back the height of the downward flexing bow to the sawhorse or chair of the supported bow, again making sure this rod is perfectly horizontal. Measure the distance between this mark and the bottom of the lifted bow.
I have some measuremnent numbers of some other platforms (boats) stiffness measured in this way; from the top of my head. (1 inch = 25.2 mm)
Tiger F18 / nacra F18 = in the range 94 - 98 mm (platform weight = 130 kg) Blade F18 = 25 mm (platform weight = 130 kg) Aging Tornado = 55 mm (platform weight = 115 kg) Taipan 4.9 (AHPC glass) = 64 mm (platform weight = 65 kg) Taipan 4.9 (homebuild ply) = 62 mm (platform weight = 65 kg) Blade F16 prototype (ply) = 45 mm ((platform weight = 65 kg) Blade F16 VWM 2007 version 90x2 beams = 15 mm (platform weight = 60 kg)
I'm told modern A-cats flex in the range of 15-20 mm when layed up like this. (platform weight = roughly 45 kg)
I have no data on the other VWM Blade F16's but I suspect they are comparable to the ply prototype Blade F16. And of course the weight of the platform must be taken into account as well, although only partially as lighter platforms also witness smaller loadings while sailing and as a result will flex less even when the platform stiffness is identical to a heavier platform.
Also note that while sailing you won't see the above measure of flexing. The test setup is a rather heavily loaded one. In real life sailing it is rare to see halve of it even in very rough conditions.
My own Taipan F16 (modified and widened Taipan 4.9 with a different rearbeam section) flexes rougly 65 mm. As an engineer I would like to have more stiffness but as a sailor I must say that I'm not finding the current flexing as an issue of any sort. I hardly ever notice any effects on the water. Sometimes my beam bolts slacken and then, yes, I feel a degradation in behaviour while sailing in wavy conditions. I don't when the bolts are tight.
If your F16 boat flexes about 2 inches or less in this test setup then you should be content with that. Your platform will have sufficient stiffness for proper handling and sailing. Any additional stiffness will be sexy.
I hope this helps
Wouter
Last edited by Wouter; 07/12/07 04:44 AM.
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Flex
[Re: PTP]
#111351 07/12/07 08:09 AM 07/12/07 08:09 AM |
Joined: Feb 2006 Posts: 3,348 fin.
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Carpal Tunnel
Joined: Feb 2006
Posts: 3,348 | . . . epoxy (use mold release, nothing permanent) G'luck! <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> | | | Re: Flex
[Re: fin.]
#111352 07/12/07 09:35 AM 07/12/07 09:35 AM |
Joined: Aug 2005 Posts: 2,921 Michigan PTP OP
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OP
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Joined: Aug 2005
Posts: 2,921 Michigan | . . . epoxy (use mold release, nothing permanent) G'luck! <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> I've done it before and it isn't as complicated as one would think. Now, the mess on the other hand.... I am not as careful as I should be <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> | | | Re: Flex
[Re: ncik]
#111354 07/12/07 06:47 PM 07/12/07 06:47 PM |
Joined: Aug 2005 Posts: 2,921 Michigan PTP OP
Carpal Tunnel
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OP
Carpal Tunnel
Joined: Aug 2005
Posts: 2,921 Michigan | On the topic of stiffness, what sort of deflection are ppl getting in their main beam under full rig tension? And, what deflection are ppl getting in their bows (transversely) under full rig tension?
I found it difficult to maintain rig tension on my ply mozzie because there was heaps of deflection in both of these. I managed to increase the dolphin striker tension which helped reduce the main beam deflection. I was always curious why my leeward stay is always flapping in the breeze even when I set the stays fairly tight on the beach. The mast slaps a little if you put it head to wind and get rocked by the waves. I looked at the main beam one day when I was out and didn't notice any significant deflection. I figured it out though- the mast is flexible enough that the sheeting on the main and the downhaul bend the mast pulling the hound lower... The HT I used to sail didn't hardly do this at all but I figure it had to be because of the HT's overbuilt carbon mast isn't as flexible. I am afraid to tighten the rig anymore - and it is pretty tight now- because I leave it mast up and don't have the time/energy to loosen/tighten everytime. Some people don't like this, but I figure the mast slamming back and forth if they are loose is worse. | | | Re: Flex
[Re: PTP]
#111355 07/12/07 07:11 PM 07/12/07 07:11 PM | Anonymous
Unregistered
| Anonymous
Unregistered | When I get the funds i am having the Hobie 17 taken apart and put back together with 4800. dealer suggested not using 5200. Going to replace all the bolts on trailer at same time. If I don't sell it first.
Doug | | | Re: Flex
[Re: Wouter]
#111356 07/12/07 07:18 PM 07/12/07 07:18 PM |
Joined: May 2002 Posts: 1,037 Central California ejpoulsen
old hand
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old hand
Joined: May 2002
Posts: 1,037 Central California | Method :
Demast the boat, so you have a bare platform.
Lay the platform up on two sawhorses or chairs so that the rearbeam is aligned perfectly horizontal.
Lift one bow and put that on a sawhorse or chair as well. Then use a rod or plank to bring back the height of the downward flexing bow to the sawhorse or chair of the supported bow, again making sure this rod is perfectly horizontal. Measure the distance between this mark and the bottom of the lifted bow.
I have some measuremnent numbers of some other platforms (boats) stiffness measured in this way; from the top of my head. (1 inch = 25.2 mm)
Tiger F18 / nacra F18 = in the range 94 - 98 mm (platform weight = 130 kg) Blade F18 = 25 mm (platform weight = 130 kg) Aging Tornado = 55 mm (platform weight = 115 kg) Taipan 4.9 (AHPC glass) = 64 mm (platform weight = 65 kg) Taipan 4.9 (homebuild ply) = 62 mm (platform weight = 65 kg) Blade F16 prototype (ply) = 45 mm ((platform weight = 65 kg) Blade F16 VWM 2007 version 90x2 beams = 15 mm (platform weight = 60 kg)
I'm told modern A-cats flex in the range of 15-20 mm when layed up like this. (platform weight = roughly 45 kg)
I have no data on the other VWM Blade F16's but I suspect they are comparable to the ply prototype Blade F16. And of course the weight of the platform must be taken into account as well, although only partially as lighter platforms also witness smaller loadings while sailing and as a result will flex less even when the platform stiffness is identical to a heavier platform.
Also note that while sailing you won't see the above measure of flexing. The test setup is a rather heavily loaded one. In real life sailing it is rare to see halve of it even in very rough conditions.
My own Taipan F16 (modified and widened Taipan 4.9 with a different rearbeam section) flexes rougly 65 mm. As an engineer I would like to have more stiffness but as a sailor I must say that I'm not finding the current flexing as an issue of any sort. I hardly ever notice any effects on the water. Sometimes my beam bolts slacken and then, yes, I feel a degradation in behaviour while sailing in wavy conditions. I don't when the bolts are tight.
If your F16 boat flexes about 2 inches or less in this test setup then you should be content with that. Your platform will have sufficient stiffness for proper handling and sailing. Any additional stiffness will be sexy.
I hope this helps
Wouter Adding to the data here. I had the opportunity to check out and handle the new geltek flyer from Australia. This A-class has glued carbon beam. Although conditions weren't perfect for the test (the platform was unrigged on a sandy beach), with the Wouter method the amount of flex was about 1/2 inch. The boat was rediculously light and stiff, a real thing of beauty.
Eric Poulsen A-class USA 203 Ultimate 20 Central California
| | | Re: Flex
[Re: Wouter]
#111357 07/13/07 12:28 AM 07/13/07 12:28 AM |
Joined: Mar 2005 Posts: 322 South Australia Marcus F16
enthusiast
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enthusiast
Joined: Mar 2005
Posts: 322 South Australia | Wouter,
Your info is not quiet correct.
The Blade F18 had its rig in place but not tensioned. Same went for the Hobie/Nacra & the Aging Tornado. If fact the Aging tornado was about 120mm of flex & the Marstrom (93 model) was about 55mm. They all had their rigs in place. The extra weight from the rig would affect your comparisons.
Marcus
Marcus Towell
Formula Catamarans Aust Pty Ltd
| | | Re: Flex
[Re: PTP]
#111359 07/13/07 07:04 PM 07/13/07 07:04 PM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Tightening the bolts worked.
<img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Told you so ! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Keep an eye on those bolts, over time the will work themselves loose again. I typically retighten my bolts about 2 a season. With a new boat in its first season I will do it roughly every 4 weeks or when I have sailed alot. In the first season the slackening of the bolts goes really quickly and you have to keep an eye on them. In the next seasons when they have become dirty and stick more easily the slackening rate goes down considerably. But still it is worth keeping an eye on them. Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
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