Proper way to power to plane

[Hampton]

On my 250, I'd trim the drive down, leave the tabs alone, push it up about 3/4, jump up on plane and trim up about 1/8 as it accelerated and I pulled the power back, then trued up the trim tabs.

In the 340, if I'm really heavy and/or feel like it, I'll trim the tabs down, but it's not required. I like to set just over 3000 RPM and let it come on up and accelerate out to about 3200 RPM, then trim tabs up (if they were down), then one down to level the bow as required. I do this because I just like the feel of the low RPM, painless way the 340 comes up on plane with the 8.1s. Not a lot of throttle required, not a lot used.

It's not a sports car, so I drive it with more finesse.

 

[skibum]

My boat plows only until it reaches planing speed. Yeah, full throttle would get me there about 2-3 seconds quicker, but I see no real benefits.

My engine philosophy is simple. Power should be applied as smoothly and evenly as possible. The engine should always "feel" a nice, even load. If I am accelerating, I apply power until the engine is pulling well. As the boat gains speed and momentum, I move the throttle up slowly to match the speed of the boat and keep the load on the engine constant. When I hit cruising speed, the load on the engine is approximately the same that it saw during the acceleration phase. When I drop off plane, I slowly back the throttle down, keeping the load on the engine as constant as possible.

Starting off with a ton of throttle just puts a ton of stress on the drivetrain. Then, as the boat gets moving and you have to back the throttles down, there is a bunch of stress on the drivetrain again as the engine slows down. The water flowing under the boat is still trying to turn the props, and now the entire drivetrain is trying to slow them down. So... my theory is that slamming the power in and then backing it off later stresses the entire drivetrain (and it does it twice) more than simply adding or removing power slowly to match the load on the engines with the speed of the boat.

Maybe I'm all wrong. I use the same technique in my cars and truck as well and I have never experienced a serious engine problem in any of my vehicles, ever. Gotta stick with whats been working...

 

[Capt Bob F]

This makes sense to me, every boat is different. I have been on a small Sea Ray that required 100% throttle and when loaded took forever to even get on plane. From reading the previous posts, many boat owners get up on plane and than reduce throttle. I always had go fast boats that required some heavy throttle to snap them out of the water and than unless you wanted to go warp speed you would back the engines down. My 480 is my first Sea Ray/cruiser style boat and there is no need at all to throttle above the desired cruising RPM when getting on plane.
down the throttle after is planes out.

I agree!

 

[glocklt4]

I'll admit with a sport boat I like to slam it and go When we get a 320 there won't be any point to that though.

 

[320Bob]

I wonder if salt water, being more bouyant, makes a difference in the way the 340 comes on plane...

I've been curious about this also but perhaps it is somewhat offset by salt water being denser than freshwater. My limited boating experience has only been in fresh water so I have no idea what the answer is.

I have a more fundamental question about planing which is how do you know when you are on plane? I would use my GPS speed change in my previous boat along with the outdrive power trim. However, my 320 has V Drives so trim tabs and speed will be the only planing tools I have to work with. I believe the Bennet Trim tabs manual on my previous boat said that you were on plane when the bow splash was as far back as possible along with the wake rooster tail being as far back from the stern. Are these two visual indicators correct?

 

[Glen S]

I wait until my temp gauges indicate the engines are at least warming up (they never seem to get to operating temp till there is real load on them). Then once clear of the harbour entrance and boat traffic I ease her up to about 2000 RPM for maybe a minute, check the gauges and then up to 3000 which is where we cruise. The way I see it, she is not a ski boat so little point in hammering on the engines to get on the plane a few seconds faster - that just has to be harder on all the running gear over time.

 

[Jimmy Buoy]

How do you know when you're on plane??:huh::huh:

IMHO when your bow wave has passed under the boat and is now behind you - you're on plane. :thumbsup:

One indication of this is that big ol "hole" behind your boat. Basically, the transom is out of the water and there is smooth water extending back past the hull. Even though this may be the case and you are technically "on plane" it may not be an efficient cruising attitude. If the angle of the boat is still "bow high" you can combine more tabs with a bit more throttle to settle the bow down for a more efficient and comfortable cruise.

I can be on plane as slow as 13kts, but all it takes is passing through another boat's wake to slow me down enough to drop off plane.:smt013 Then it takes a great deal of energy (which is $$) to get back on plane. It's better to be solidly on plane at a higher speed so variances like wind, wakes, turns etc. don't drag you off plane.:smt038

Also, boat loads like passengers:wow:, fuel, water, and provisions can make the same boat plane at a different speed and tab usage.

I'm sure a CSR member in your area would be willing to go for a cruise with you on your boat and go through the basics so you will know for sure!:grin:

 

[320Bob]

"IMHO when your bow wave has passed under the boat and is now behind you - you're on plane. :thumbsup:"

Thanks Jim,
I have asked this question a number of times to others and this is the first time anyone has provided this explanation. I could not observe this on my sea trial when the salesman was at the helm but he said the boat was on plane at 3000 rpm. Since the GPS was not hooked up and the speedometer paddlewheel was broken, I could not equate this to any measured speed.

BTW, what is the difference between your 340 Amberjack and a regular 340 Sundancer?

 

[Lazy Daze]

Salt water?

Back when I had my 210BR, I did that exact experiment. Using GPS and going both with and against the current, then averaging the two, I found the boat to be a solid 2MPH faster in salt. I kept everything else the same - same amount of fuel (within a few gallons), same load and just me in it. Ambient Temp was almost the same. The only slight variable was altitude - the lake I was on was at about 600'. But, I don't think 600' would matter much.


Nice explanations of how to know when a boat is on plane! I've never tried to say it so eloquently - and I don't think I could have if I tried. :smt001

 

[320Bob]

Salt water?

Back when I had my 210BR, I did that exact experiment. Using GPS and going both with and against the current, then averaging the two, I found the boat to be a solid 2MPH faster in salt. I kept everything else the same - same amount of fuel (within a few gallons), same load and just me in it. Ambient Temp was almost the same. The only slight variable was altitude - the lake I was on was at about 600'. But, I don't think 600' would matter much...:smt001

I thought there might be a difference but I was unsure how much impact increase boyancy would have. Were the rpms the same is each case. If so, then I a guess reducing the wetted area makes the boat go faster.:grin:

 

[Jimmy Buoy]

"

BTW, what is the difference between your 340 Amberjack and a regular 340 Sundancer?

The Amberjack was previously the Express. It's a completely different hull with a 13'5" beam for the 34' length. The engines are under the helm area, and the helm is further forward than normal. This makes the cockpit seem more like a 40'.

Engine access is great since the entire helm floor raises electrically, exposing the mains, genny, and all other services with room to walk between and in front of the engines. The straight shafts are easier to access than v-drives and they provide more or the engine's torque to the props too.

The downside is that the cabin although wider than normal is shorter in length and lacks an aft cabin. This boat is really designed for a couple that like to sleep in the same bunk, but like to entertain. Sure, guests can come along for the cruise, but they'll want to be in a B&B come bed time! :lol:

With more of the boat's weight forward, there is less bow rise getting onto plane, and being heavier allows more confidence in heavy seas. Marketed as a fisherman's dream that can satisfy his first mate's quest for luxury it was a low production model with a hefty price tag. That makes it rather rare and always draws the curious with questions. Although it's a great conversation starter.:thumbsup:

Glad I could help with the planing thing.