Speed effects on weight and weight distribution when skiing

hughescpa

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I have a 24ft L series tritoon with 150HP 4 stroke Merc purchased new this year.

I haven't had any trouble skiing in the past but have had 5 people or less on the boat.

My top speeds on the boat have been about 36mph.

This weekend I had a 10 people (4 kids) on the boat and couldn't get above 22mph. We skied, but took it took a while for the adults to get up and couldn't get going fast enough to ski well. I had it open full throttle while skiing. RPM were about 4500-4600

My questions:
1. Does the extra weight have that much of a dramatic drop in top speed? Or is there something else I should be checking on the boat?

2. Is there a recommended weight distribution (e.g. put the heavy people in back) to increase hole shot and top speed? Or are there any other tricks of the trade to maximize hole shot and top speed?

3. Should I put the trim up more once I get a skier up? I did that but seemed to only increase speed about 1mph.
 
Do you keep it in a slip or use a trailer ? Algae growth on the toons will slow you down a lot as will the added weight .
I was able to get my previous 23 RCW SA ( much heaver boat ) to 38 with a Merc 150 . Full tank of gas ,gear, just my wife and I .
What prop are you running ? I had a 15 X 15 Enertia
 
Jack asks some great questions. Not sure what the recommended WOT RPM range is for your engine but what you report seems low. That said, having a full crew aboard along with the supporting provisions will definitely have an impact on your engine's overall performance. If you do have your prop dialed in, then there may not be a whole lot you can do. However, there are a number of folks on this forum running similar boats that should be able to weigh-in on the subject. BTW, post some pictures of your new Benny!
 
Do you keep it in a slip or use a trailer ? Algae growth on the toons will slow you down a lot as will the added weight .
I was able to get my previous 23 RCW SA ( much heaver boat ) to 38 with a Merc 150 . Full tank of gas ,gear, just my wife and I .
What prop are you running ? I had a 15 X 15 Enertia
I trailer it and take it to local reservoir. I haven't washed it yet so it doesn't look brand new anymore but no algea or growth on the toons. I have 30 hours on it this summer.

It seemed really dogged this weekend and the only thing that changed was probably about an extra 750 to 1,000 pounds of people.

Factory prop.
 
Your dealer installs the prop as part of the rigging . With 30 hours you may have some slime ,if there is no slime on your toons , find out what size prop you have . With a 150 ( or better ) they should be Stainless Steel . If you are worried about hitting something ,get a flo-torque hub .

 
Your dealer installs the prop as part of the rigging . With 30 hours you may have some slime ,if there is no slime on your toons , find out what size prop you have . With a 150 ( or better ) they should be Stainless Steel . If you are worried about hitting something ,get a flo-torque hub .

I'd say there is slime on it. Yes Dealer rigged. Stainless steel prop. I don't know pitch or model.

What does the Flo-Torq Hub do?
 
The extra weight has a huge effect on performance. More weight on the boat, more boat being displaced into the water, more drag to overcome by a 150hp engine. Add on an adult skier on the back, more drag.

As far as loading, ive always put people up front to help get the skier up.

ultimately at 24', and wanting to pull a skier, you'll need a bigger engine or take less people.
 
That slime may be your culprit .
Since the Stainless is stronger than an aluminum prop ,the hub ( supposed to ) breaks before any damage is done to your motor . Yet you can still get home .
 
For reference with my 250hp motor, I lose around 1.5 mph if I have a full tank (52g) vs a half tank. 26 gallons weighs around 170lbs. so using that for reference 1000lbs / 170 x 1.5mph = 9mph expected loss of speed if I added 1000lbs to my boat.

That's for a 250hp V6 with big torque and a large prop that can overcome the additional drag and weight. So I'm not surprised with your bigger speed drop with that I4.

However 14mph does seem a bit high. As others have alluded to, your prop may be contributing to your loss of speed - without enough prop blade area (usually diameter determines this but not always) as drag increases some of your power slips off the prop and is not converted to forward thrust. But with your RPM dropping to 4600 at WOT that tells me it is doing a moderately good job at gripping the water. There may be a prop solution here but I don't think it will be a silver bullet. You need more power, period.

Weight distribution for hole shot is only important if you are ventilating - i.e. your prop is drawing in air because it is too close to the surface and is losing grip. If your motor is mounted in the lowest position this likely isn't an issue. But if so you can back load your people aft to help offset this - once on plane you'll then want to get more of the motor (lower unit) higher in the water column to reduce drag for optimal speed, so move them around more equally front to back. Or just get a bigger motor!
 
Plain and simple. Your 150 is a very capable engine. (I have the same one) But you have too many people on the boat when trying to pull an adult skiier! You are making that 150 really work to carry all those people AND pull somebody out of the water. We never trim up while skiing........
 
One thing to check is if you have water in your pontoons. I just had our 2018 fixed this spring and also had a leaking toon on a 2008 previously. It’s more common than a lot of people think. It doesn’t take much water in the toons to make a big difference on performance.
 
You should read your owners manual on your 150. There is a break in period. Check it out. You shouldn’t running wot until after 20hrs and maybe more on the 150 but yes the weight 10 people plus 4 kids that’s probably 1800lbs or more. Or 6 adults and 4 kids that still a lot with provisions coolers etc. but if your pontoon is a 2 toon your probably not getting up on plain.
 
Assuming the tubes are clean - re prop for that extreme load and you will definitely see an improvement.

Multiple Large Ice Chests and Multiple Large Peeps are not the friend of a 150 shod Toon but getting the engine up to 56-5800 will at least get you close to a happy skier situation!
 
Welcome to the club! I’dverify your prop and start there. My boat is a 24SSLX W/Evinrude 200hp (non HO-don’t ask) Our boat did 42 with the prop the dealer installed. Boat handled ok. Switched to a 15pitch rebel from a 16pitch viper and man what a world of difference. Almost 30% less fuel consumption, no prop blow out when tubing and the boat handles much better, lost 2mph on top. 7 adults last week 3/4 tank and coolers still pulled 36mph. Amazing what a prop can do!
 
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