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Horsepower Requirements

Old 09-10-2020, 05:56 PM
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Default Horsepower Requirements

Looking to purchase a new 21' center console w/offshore hull. The max horsepower is 200, and they offer various versions of the 150 and 200 hp Yamahas. In general, they are asking roughly $4000 more (depending on variation) to go up from 150 to 200 hp. I'm on a budget, and don't want to spend more than I need to. Most of the time I'll have between 2-4 people (with gear) on board. I'm not interested in going fast, but I do want to be able to get on plane without struggling in 1 foot seas. I've seen other threads where it was stated 75% of max hp is sufficient, which in this case would be 150 hp. So, do I really need to open my wallet for the extra 50 hp? Or will 150 hp do the job reasonably well?

Last edited by h_bar; 09-10-2020 at 06:19 PM.
Old 09-10-2020, 06:23 PM
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Which 21’ boat exactly?

Some are light and 150 is plenty, others I would never buy unless it had a 200.

My last boat was a 20’ Key West with a 150. It was rated for a 200, but no one got the 200. Topped out at 47 with the 150 but was not stable at that speed. That boat was too light (1900 dry weight).
Old 09-10-2020, 06:30 PM
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it would be helpful at the least to know the dry weight of the boat, fuel capacity, and the deadrise. a specific model would even more helpful.
Old 09-10-2020, 06:33 PM
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A 150 on a 21’ sounds about right. But what boat? Some 21’s can be heavy an need a 175, but a 200 for someone on a budget seems a bit much.
Old 09-10-2020, 06:34 PM
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Which 21’? Offshore hull doesn’t tell enough to know.
Old 09-10-2020, 06:42 PM
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Sportsman Open 212. Dry weight is 2300 lbs. Which appears to be about average for that size. Maybe a little heavier than average, but not by much.
Old 09-10-2020, 06:44 PM
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You would be fine with a 150 hp engine on that boat.

Last edited by MTSkibum; 09-10-2020 at 06:53 PM.
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Old 09-10-2020, 06:50 PM
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If you give the make and model there are probably lots of people on this forum that can tell you what engine it needs.
Old 09-10-2020, 07:06 PM
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Keep in mind the weight difference too. How much more weight for 50 HP? Money aside, it likely isn’t necessary.
Old 09-10-2020, 07:09 PM
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Originally Posted by Still Stoked View Post
Keep in mind the weight difference too....
What weight difference are you referring to here?
Old 09-10-2020, 07:11 PM
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Originally Posted by Still Stoked View Post
Keep in mind the weight difference too. How much more weight for 50 HP? Money aside, it likely isn’t necessary.
Its the same engine just tuned different, no weight penalty.
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Old 09-10-2020, 07:19 PM
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150 would be fine, but sea trial it first then decide. If buying new and keeping it a long time, get exactly what you want though. That may mean opening up the wallet a little bit.
Old 09-10-2020, 07:24 PM
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Originally Posted by 69Mach390 View Post
150 would be fine, but sea trial it first then decide..
Thanks. I have no doubt the 150 would be fine with two aboard. My concern is 4 to 6 people with gear . Kinda difficult (although not impossible) to arrange to duplicate that during a sea trial.
Old 09-10-2020, 07:27 PM
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Originally Posted by h_bar View Post
Thanks. I have no doubt the 150 would be fine with two aboard. My concern is 4 to 6 people with gear . Kinda difficult (although not impossible) to arrange to duplicate that during a sea trial.
Not hard at all, I brought the whole family on my sea trial. Kids up front, wife in “her seat,” father in law plus the salesman. How else would you want to test out a boat? Test it like you’ll run it!
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Old 09-10-2020, 07:28 PM
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https://yamahaoutboards.com/en-us/ho...2012-12-06_occ


https://yamahaoutboards.com/en-us/ho...2013-07-11_occ

Thats 2 boats with the same load.

The 150 actually turns more pitch. That should tell you something. Its within 50 rpms of the 200 at WOT with more pitch.


The 150 is 1 mph slower in the midrange and 2 mph's slower at WOT. Hardly any difference.

When Sea Hunt tested the 200 on the BX 22 when it first came out. The engineer said almost no difference over 150. A lot of the bulletins prove that.
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Old 09-10-2020, 07:29 PM
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I just put a DF150 on my 22’ Bay, weighs 2400 lbs, after extensive research. Max is 250 hp. Wot of 40 mph @ 5500 rpm - less than reports but okay for me. Another point to consider - F200 requires 89 octane fuel which is hard to find at some marinas.
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Old 09-10-2020, 07:34 PM
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Originally Posted by captain28570 View Post
....When Sea Hunt tested the 200 on the BX 22 when it first came out. The engineer said almost no difference over 150. A lot of the bulletins prove that.
I actually did compare the 150 vs 200 engine performance reports. I noticed they use half tank fuel and minimal weight aboard in ideal wx conditions. Not really typical conditions at all. Again it appears 150 is plenty of hp with basically an empty boat. Just concerned what difference real life conditions have.
Old 09-10-2020, 07:38 PM
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You would be fine with the 150hp. Divide the boat weight by the horsepower. If the result is 16 or under, you are fine. You can ignore engine weight for this test.

There is only a 2 lbs. difference between Yamahas 150 and 200. My boat weighs 2350 (engine is 401 lbs). Fast as you could want.

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Old 09-10-2020, 07:41 PM
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Originally Posted by h_bar View Post
Thanks. I have no doubt the 150 would be fine with two aboard. My concern is 4 to 6 people with gear . Kinda difficult (although not impossible) to arrange to duplicate that during a sea trial.
That's why we have different props available. Changing props is like changing gears. If you want 6 people, ice, and beer, then you go to a smaller pitch prop so you can still get the power you need, but you'll have a lower top speed.
Old 09-10-2020, 07:44 PM
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Originally Posted by h_bar View Post
Looking to purchase a new 21' center console w/offshore hull. The max horsepower is 200, and they offer various versions of the 150 and 200 hp Yamahas. In general, they are asking roughly $4000 more (depending on variation) to go up from 150 to 200 hp. I'm on a budget, and don't want to spend more than I need to. Most of the time I'll have between 2-4 people (with gear) on board. I'm not interested in going fast, but I do want to be able to get on plane without struggling in 1 foot seas. I've seen other threads where it was stated 75% of max hp is sufficient, which in this case would be 150 hp. So, do I really need to open my wallet for the extra 50 hp? Or will 150 hp do the job reasonably well?
Probably not a huge difference but personally I would NOT buy the 150 and would absolutely go with the 200.

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