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| Planning question https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=3921 |
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| Author: | 1NiceHarley [ Tue Jun 30, 2009 10:08 pm ] |
| Post subject: | Planning question |
OK did a search couldn't find what I wanted to know. I have started to learn to wakeboard. When the boat planes we are going faster than I want to. Right now we have a 14 1/4 x 21 three blade aluminum prop. If I change it to (our spare) a 15 x 17 prop three blade aluminum, will that plane us earlier/at a slower speed? When the boat isn't on plane, it is too hard to keep at a constant speed. I know if I swap to the spare prop I will have to watch our RPM but I really don't care how fast we go. If we are traveling faster than 30-35 mph we are going to fast. Boat info. '94 180 Horizon, 5.0L OMC Cobra, 1.66 gear ratio, WOT 4200-4600 RPM, Original Prop (as far as I know) 14 1/4 x 21. Don't know WOT MPH. Thanks for the help. I might have to just buy a Fat Sac for the bow of the boat to help the boat plane at a slower speed and throw a larger wake. Right now I don't need the larger wake though. Just a slower speed that I can hold consistently. Thanks again, |
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| Author: | M3eater [ Wed Jul 01, 2009 7:56 am ] |
| Post subject: | Re: Planning question |
Yes, the 15 x 17 prop will pull you up quicker. However, it will not really change the planing speed. The 15 x 17 prop will allow you to control the engine speed and the boat speed a little more accurately, but as noted, will not appreciably change the planing speed. A four blade prop will help to reduce the planing speed ..... a little bit. It does this by providing more lift at the rear of the boat. If you want to substantially lower the planing speed, you may have to look into a set of trim tabs. |
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| Author: | 1NiceHarley [ Wed Jul 01, 2009 9:09 am ] |
| Post subject: | Re: Planning question |
I was afraid of that. Didn't really want to put the tabs on it. Does any one have a picture of the Trim tabs on their boat. Hopefully with a similar hull design as ours. Will putting a ballast in the bow of the boat help plane at a lower speed? |
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| Author: | DaleG [ Wed Jul 01, 2009 11:03 am ] |
| Post subject: | Re: Planning question |
Go with real trim tabs -- you will find lots of other good features about them -- such as leveling the boat when three guys are all sitting on the same side ---or getting up on plane to ski when you have five people on the boat --- etc --- don't resist the dark side -- just do it |
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| Author: | BrentC5Z [ Wed Jul 01, 2009 11:36 am ] |
| Post subject: | Re: Planning question |
They will also help you acheive a higher top speed without porposing. (not that you may care, but I DO!)  The ballast will not actually change the planing speed either. I've tried a 400# bag and two people up front. It still fought to try to go faster. Planing speed is totally contributed to hull design IMHO. |
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| Author: | pet575 [ Wed Jul 01, 2009 12:12 pm ] |
| Post subject: | Re: Planning question |
You need to make a decision re: wakeboarding. What are you goals? Do you want to just be able to ride it around and do some slides or maybe surface 180's? Or do you want to be able to jump wake to wake and maybe try to learn some tricks to pull off while you're in the air? If you want to do ANY kind of wake-jumping stuff down the line, then avoid trim tabs at all costs. They will wreck your wake and you will never be able to steepen the wake so long as the trim tabs are in use. You should be riding at speeds between 18-21 MPH. Using a lower pitched prop WILL help you hold the lower speeds more consistently even if it doesn't improve a lot of other performance-related matters. Most I/O owners use a 4 or 5 blade prop to accomplish this, I would recommend you do the same. |
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| Author: | ht32bsx115 [ Wed Jul 01, 2009 12:19 pm ] |
| Post subject: | Re: Planning question |
Hmm, I thought this was a planning question.....  I have Bennett Sport Tabs on my Liberator. When I pull a Wakeboard-er I run the tabs all the way down and run the drive trim all the way IN and I am able to control the speed pretty well. (and I can keep the bow down)...... most people want to run at about 18-22 MPH on a WakeBoard. Too slow and it's very hard to hold on.....Most people don't want to go very fast either. Since most boats want to break into a plane at that speed so you have to watch your speed pretty close. Tabs and mainly drive trim will control where (speed) it starts to plane. If you run the trim out (engine up) it will prevent planing at slow speeds.....but you'll have to experiment with drive trim... This is something a sterndrive has it all over an inboard. 4 and 5 blade props are ok I guess they're not cheep though! I like my "6 blade" prop. I can really control the speed! Smart Tabs are spring loaded and can be adjusted manually ....All tabs cause drag. so they'll always kill your top speed if they touch the water when you're going fast. Drag also means more fuel burn. Here's what mine look like.  Cheers, Rick |
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| Author: | 1NiceHarley [ Wed Jul 01, 2009 1:16 pm ] |
| Post subject: | Re: Planning question |
Our boat planes about 20 Mph (speedo) I am going to check with GPS this week end. Right now I am just learning the basics on the wakeboard. And I rather be at about 16-18 mph. In the future (probably a couple or weeks or so before I am confident enough) I want to start learning the jumps. So, Pet575, the trim tabs mess up the wake? Well crap I don't want to do that. Maybe I will just have to suck it up and learn the basics at a little faster speed than I want. It just hurts more when I screw up and wipeout. LOL I have 2 friends with wake boats, one Malibu and one Tige, I just don't want to have to rely on them to help me learn. They won't take money for gas, so I don't want to use theirs because of the price. I feel bad using someone elses gas to learn. I rather use mine. Thanks for input! Keep it coming! |
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| Author: | pet575 [ Wed Jul 01, 2009 3:05 pm ] |
| Post subject: | Re: Planning question |
1NiceHarley wrote: In the future (probably a couple or weeks or so before I am confident enough) I want to start learning the jumps....I have 2 friends with wake boats, one Malibu and one Tige. I'd work out a deal where they take gas money (or don't) and agree to add me to their crew for riding. No matter what we do, our boats will NEVER put out the wake quality that a Bu or a Tige does for jumping/tricks. If you can work out that type of deal, it is going to save you a lot of headache and displeasure when comparing your boat's performance/wake to those. Take advantage of their specialty boats and then take them for cruises down the lake when it is choppy out. |
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| Author: | boater [ Wed Jul 01, 2009 3:06 pm ] |
| Post subject: | Re: Planning question |
OK, I'll input. "And I rather be at about 16-18 mph" A 19" 4 blade should do that for you. I put one on last year. I can keep plane at about 16 or 17. Do you have a prop shop that will let you try a couple? |
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| Author: | 1NiceHarley [ Wed Jul 01, 2009 3:13 pm ] |
| Post subject: | Re: Planning question |
boater wrote: OK, I'll input. "And I rather be at about 16-18 mph" A 19" 4 blade should do that for you. I put one on last year. I can keep plane at about 16 or 17. Do you have a prop shop that will let you try a couple? So my 17" will probably do the same? |
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| Author: | boater [ Wed Jul 01, 2009 4:38 pm ] |
| Post subject: | Re: Planning question |
Maybe. It won't cost you anything to try it. I'm no expert, I just think the extra blade helps. |
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| Author: | ht32bsx115 [ Thu Jul 02, 2009 4:43 pm ] |
| Post subject: | Re: Planning question |
In reality, the type of prop or number of blades doesn't make any difference in planing. A boat planes based on the center of gravity, weight and speed (due to thrust). If it's a stern drive or an outboard, the amount and angle of thrust will make a difference (since you can vary it either manually or hydraulically) If it's an inboard, you can only vary the amount of thrust (with the throttle).....the angle is fixed. You can change things a little more by applying more upward force with fixed or adjustable tabs. You can also vary the CG by having people in the boat move around. And if you have one of those new-fangled $100,000 "Wakeboard" boats, you can do it by pumping water into or out of bladders inside the boat. |
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| Author: | boater [ Thu Jul 02, 2009 5:29 pm ] |
| Post subject: | Re: Planning question |
Quote: In reality, the type of prop or number of blades doesn't make any difference in planing That's easy for you to say. You have 6. Lets see you plane that thing with 2. 
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| Author: | ht32bsx115 [ Thu Jul 02, 2009 7:53 pm ] |
| Post subject: | Re: Planning question |
2 blade props aren't all that good for "run-a-bout boats" but they are used on some very fast boats. http://www.propellerman.com.au/2blade.html  There is a happy medium though in 3 blade props for most boats. I suspect a lot of people get 4 and 5 blade props because they look cool (and they do look cool!) but you really can't see them when the boat is in the water. They cost a fortune and IMHO....don't really deliver the performance commensurate with the cost. |
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