SoCal Jet Boats
Tech Talk => Hulls => Topic started by: Brad @ SCJB on October 25, 2007, 08:57:55 PM
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For the circle boat application, would you want rounted or sharp strakes?
also, what would be the reason/advantage to taper off a strake like this:
[attachimg=1]
[attachimg=2]
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The sharper they are the better they hold as well as drop the water and not create drag. It looks like there is a bit of hook that needs to come out. I would only worry about hook from the keel to the first strake. It looks like they were trying to create some rocker to make it faster. As well as get some bow lift.
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get that thing flipped over allready ;)
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"Brad] 1:39 pm: i'd do it if i had a fuckin boat
[Brad] 1:40 pm: no time to work on it anymore
[bkplesh] 1:41 pm: take it to jim
[cj410] 1:41 pm: why, so omar can pass brad too"
THAT IS FREAKING HILARIOUS! sorry for the distraction...
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The sharper they are the better they hold as well as drop the water and not create drag. It looks like there is a bit of hook that needs to come out. I would only worry about hook from the keel to the first strake. It looks like they were trying to create some rocker to make it faster. As well as get some bow lift.
no offense Jim, but I'd rather get some input from someone else....your boat handles like crap.
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I use a strake on my front yard...Brad's one rude son-o-a-bitch! No offense...LOL!
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Brad.
This picture #1 shows rocker as I am sure you know.
Rocker is good in most respects. It will allow a wider area in wich the hull will perform. Most set ups will need some rocker or or you will get a porpous(not all). For a circle burner you will need good midrage performance in the corners and of course good straight line speed. One will effect the other! In a straight line you want the strakes to add lift to reduce drag. Entering the corner you want the boat to settle down and increase wetted surface for control and manuverability. It is dang near impossable to tune a bottom you have not ran. Tuning the bottom for turning done buy feel. What is right for them may not be whats right for you. To answer you on the shape it will more than likely be both. You want the water to exit the strake a clean as you can IE sharp. With sharp strakes you run the risk of the boat feeling twitchy or wanting to hunt in the waves, in this case you need to dull the edges. Your own driving style has a huge impact on strake shape. Placement and size are much the same but add power and weight to the mix. The second pick is much more interesting. Note how the stake gains width toward the transom ;D
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Thanks for the info. I will take all of that into account when (if) i get this boat in the water and start to create a roadmap for the bottom depending on how it handles.
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Brad, do you have any pictures of the bow? Do the strakes run parallel to the keel or follow the entry? this will also effect how the hull will feel when crossing waves at shallow angles. If the hull is overly wet on the inside corners at the transom during turning changing the Chine to a reversed will add lift in that area. If the hull wants to skip as most of you have take chine away and get the inside wetter. I know you So Cal types would never think about removing the side fins on you intake ;D But that is a good place to start. They have an effect on the roll center and dont do much for loading. The worst part is the placement. If you run a forward skag and the skags on the pump you have one fighting the other. Think about it the way it is. The forward skag is your pivot the nozzel is your force and direction. With the fins on the intake the pivot and fulcrum are way to close together. Another band aid is to put a skid fin on. (only use as a temp patch to test) nothing beats good bottom work. That is why when a boat from yester year worked they would splash it. Adverage Joe WILL NOT take the time to do it right. same for most racers. When you get running take lots of high quality video. A trick we use is to place a strip of 1" black tape every 5" on the keel strakes and chine. Gives you a great visual on how the water is moving from under the hull that can be measured at a glance.
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... I know you So Cal types would never think about removing the side fins on you intake ;D But that is a good place to start. They have an effect on the roll center and dont do much for loading...
I think I read that somewhere, but it wasn't from a So Cal type... I think...
Sounds like bottom feeder know's his sh!t.
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I use a strake on my front yard...
I had a strake wrapped in bacon for dinner last night.....My boat dont have any of those funny fins on the bottom.
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Brad your strakes are bent in the right direction... if they went the other way I'd suggest skiing only. I can't remember if Jeff B. worked on them or not but I think he may have.
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Brad your strakes are bent in the right direction... if they went the other way I'd suggest skiing only. I can't remember if Jeff B. worked on them or not but I think he may have.
Craig said in a email a few months ago that Bennet did the bottom probably twice.....it handled great...it felt better in chop then on glass.
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You need to wright the PR for Jeff to bring in the work....
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Racer Jim
"The sharper they are the better they hold as well as drop the water and not create drag. It looks like there is a bit of hook that needs to come out. I would only worry about hook from the keel to the first strake. It looks like they were trying to create some rocker to make it faster. As well as get some bow lift."
no offense Jim, but I'd rather get some input from someone else....your boat handles like crap.
LOL :D :D :D :D