2006 Larson LXI 210 prop performance

WI_boater

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Sep 20, 2020
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Just bought a 2006 Larson LXI 210 and it had a 21 pitch prop. It also has the lifters on the back to help push the back of the boat up to help plane out faster. I really think the boat should still plane out faster than it does. Any feedback on what others using for props on this boat? Debates on going to 19
 

Texasmark

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Dec 20, 2005
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What's your engine rating for max rpms. What are you currently running for rpms with your "normal" load of folks and gear at WOT? Are you interested in hole shot, WOT performance, or pulling water toys or cruising with a full load? Since you already have trim tabs, are they fixed or hydraulic? What's the duration of your current hole shot....time from when you hammer down on the throttle till the bow falls back down? What is the dead rise of the hull at the transom?
 

harringtondav

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May 26, 2018
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The options for changing any boat's performance with a prop are limited. Assuming your engine is performing well and delivering designed power, you pretty much have what you have. Available power vs. boat weight and hull design are fixed.

The trim tabs are a previous owner's add on attempt to improve this fixed performance. You may be simply a little short of power. What engine do you have? With less than full passenger and fuel load a correct prop should have the engine run at 4400-4600 rpm at wide open throttle (WOT). Your speed here is pretty much fixed based on the boat's power.

Reducing prop pitch will increase WOT rpm and improve hole shot, but likely reduces top speed. Increasing pitch will decrease WOT rpm and may increase speed - if you have enough power.

Your answers to Texasmark's and my questions will help us help you evaluate your prop questions.
 

WI_boater

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Sep 20, 2020
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I totally forgot to check the RPM's at top speed. Top speed was 51 which is fine and I'm ok with losing a bit of that to increase hole shot. I just bought the boat so I haven't tried pulling a skier but it seems a little slow. I also have those automatic trim tabs on the back which is suppose to help.
 

jbcurt00

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Avoid posting to old inactive topics like the 21 vs 19 pitch prop Larson topic you posted to.

Erikste hasnt been on iBoats forums in over 8yrs, not likely to get or respond to your post.

Good luck w your Larsons prop choices
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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there is a sticky at the top of the forums titled "read this first"

https://forums.iboats.com/forum/gen...p-questions-and-topics/295058-read-this-first

ESSENTIAL DATA REQUIRED
When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight
 

WI_boater

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Sep 20, 2020
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So the boat is a 2006 Larson LXI 210. The weight is 2925 lbs. The current prob is an Apollo Stainless Steel 14 3/4" X 21" RH prop. The motor is the 5.0 GXI which is 270HP. The motor has 470 hrs on it and runs perfect. My goal is to improve hole shot without decreasing top end speed too much. I am just curious if anyone has the same boat and has used a 19" pitch prop so I can see what their performance was like with it.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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what is your top speed and RPM?

you cant improve hole shot and keep top speed. to improve one, the other has to suffer. its a trade-off.
 

WI_boater

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Sep 20, 2020
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Yes, I am aware that 1 will suffer but am wondering how much top speed i will lose if I were to drop to a 19" pitch prop. My top speed is 51-52 but i forgot to look at my RPMs.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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every 2" jump in pitch raises your WOT RPM by 400 RPM (about 200 RPM per inch). so you will be over-reving if you are at the top level of your WOT RPM window.

we need to know your WOT RPM to be able to answer your questions..... see post #6
 

WesNewell

Chief Petty Officer
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Jan 3, 2018
Messages
497
Yes, I am aware that 1 will suffer but am wondering how much top speed i will lose if I were to drop to a 19" pitch prop. My top speed is 51-52 but i forgot to look at my RPMs.

You may or may not lose any top speed going to less pitch. For instance, if you are running only 4400 rpm now and you drop to a 19P prop and the max rated rpm is 5000 rpm, then the rpm will go up to say 4800 rpm and you will maintain about the same top speed. But your acceleration will improve. It's pretty simple really.
 

WI_boater

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Sep 20, 2020
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Thanks everyone for the feedback. I will verify my RPM's at max speed and touch base again.
 

QBhoy

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Mar 10, 2016
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If it helps and having a similar mercruiser variant of your engine...try and aim for the engine rpm to be above 4800 at wot. In my experience they must have their peak power about there. Despite having the low end of the range at 4600...if you go up in pitch and result in having 4600 rpm wot...the boat will actually be slower and a total dog out the hole. Been there and done that. Some make the mistake of thinking as long as it’s in the Rev range...more pitch equals more top speed. It doesn’t. In my experience with these short block MPi gxi v8s anyway.
 
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