14 foot deep v with a 20hp 4 stroke... - Colorado Fishing Forum

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Old 08-02-2019, 10:31 AM   #1 (permalink)
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Default 14 foot deep v with a 20hp 4 stroke...

Hey Everyone,
I've had a 14' Lund deep V and I recently purchased a used 2011 Merc 4-stroke. I'm not getting close to what I was hoping for a top speed and I'm wondering what other ppl are running here in Colorado and what their results are. It had a 10 pitch prop and I just bought a 12 pitch that I'll be returning after I tried it last night and it was slower than the 10. Topping out at a little over 16 mph with the 10. I'm going to try an 8 pitch this time around since the 12 wasn't getting high enough RPM's. I installed a jack plate that helped but I could still move it up an inch to get the hydrofoil just above the prop even with the bottom of the boat. I've gotten rid of as much weight as I can but I suspect the entire rig is between 900-100lbs. The max on the spec plate is 925 loaded so I know I'm overweight but it is what it is. I typically run between 9500' (Spinney) and 4000' elevation. The motor specs for this outboard are 5250-6250 rpm. I feel like my motor is about the right height, batteries are up front and it seems pretty well balanced. Carb was just re built by BPS in Denver. I guess my question to ppl who own a similar setup is:
1- What pitch prop are you running?
2- What is your top speed?
3- Whats your speed difference at high vs. low elevation?
4- Any suggestions for getting more speed?
5- Is there something inherently wrong with this setup?

Thanks for any help or suggestions you might have. I appreciate input from ppl who might have already experienced some of the frustration I'm going through right now.
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Old Yesterday, 08:13 AM   #2 (permalink)
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Change elevation, change prop pitch.
You will have to do experimenting at the different elevations to get the best performance.
Knowing your rpms is a must to do it right.
Higher elevations require a lower pitch.
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Old Yesterday, 08:36 AM   #3 (permalink)
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Also, the hp/speed/performance of your outboard is drastically reduced at our elevation. In other words what a 20hp motor will do at sea level is a lot more than you will get out of it here... you may be getting all you can except for a few mph difference with prop changes.

Last edited by ghostman; Yesterday at 08:52 AM.
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Old Yesterday, 09:18 AM   #4 (permalink)
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Quote:
Originally Posted by ghostman View Post
Also, the hp/speed/performance of your outboard is drastically reduced at our elevation. In other words what a 20hp motor will do at sea level is a lot more than you will get out of it here... you may be getting all you can except for a few mph difference with prop changes.
You lose 3% HP for every 1000' elevation in a NA engine. So, Front Range -15%, at Spinney you are almost down 30%.

Elevation is a killer.
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