How much HP for my 17 Glasstream bass boat?

btbowhunter

Recruit
Joined
Mar 24, 2011
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4
OK, right off, I'm betting this question will seem bizarre to some. I have a 1988 17' Glasstream Hydrabass. Bought it pretty fair a few years back with a Mariner Inline 6 115 HP. The boat tops out around 46-48 on my GPS with a light load. Thats with a 24P stainless prop that came on the boat. The motor runs fine now that I've rebuilt carbs, lower unit and a few other little things. My unusual question is that we do a trip to Canada every year where the lake is 24 miles long and runs can be fairly long to our favorite fishing spots so I'm thinking of downsizing in motor HP to burn a bit less of that 1.50+ per liter gas we have to buy up there. We've had a few trips where the gas bill was substantial including the one we just returned from. (weather was great and fishing was very good)

The boat is 700 pounds dry and can handle up to a 150 HP per the specs here. It'd usually be loaded with two adults, a full load of fishing gear, fuel, and enough drinks and sandwiches for the day. Hopefully we'd need full livewells. I'm trying to weigh the benefits and drawbacks of dowwnsizing the HP without going too far so that the boat would be tough to get on plane. A top end of 30-35 would be fine.

I'm thinking a 90 might still be enough motor for my use and should create a 20% better fuel bill.

Thoughts?
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: How much HP for my 17 Glasstream bass boat?

Any 4 stroke or DFI 2 stroke, like the ETEC in the 100-150HP range should improve your fuel efficiency dramatically. I wouldn't go down to 90HP, that is less than 70% of rated max power.
 

rallyart

Lieutenant Junior Grade
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Jun 7, 2008
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1,175
Re: How much HP for my 17 Glasstream bass boat?

The efficiency of the engine will dictate your fuel use, not the horsepower. The HP makes a difference if you are at full throttle. If you want to travel at 45mph a 100 or a 150 will give you the same economy at that speed if the engines have similar technology. Of course, if you put a 150 on it and travel at 55mph you will use more gas, but not if you travel the same speed.
If 35mph is okay for you, then just travel at that speed with your 115. It takes a lot of fuel saved to pay for a new engine.
 
Joined
Oct 22, 2007
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2,598
Re: How much HP for my 17 Glasstream bass boat?

I'd bet that if you ran 30 to 35 you'd get nearly the same fuel burn with a 90 as with your 115 running at the same speed. What people don't realize is that to run a given boat at x miles per hour is going to take the exact same power no matter what engine you have. And it's going to take pretty much the same amount of fuel flow to produce that amount of power, regardless of engine size (within reason), ASSUMING you're talking about comparable engine technologies. The only way you're going to gain much in fuel efficiency is to go to a different (newer) engine technology, as JB suggested.
 

gm280

Supreme Mariner
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Jun 26, 2011
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14,585
Re: How much HP for my 17 Glasstream bass boat?

I actually owned a 15' version of that exact same boat with a 115 HP Mercury inline 6. It would fly at 63MPH, but as you know it did go through a lot of gas to arrive at those numbers too. I'm with the other posters on this one. Just throttle back and cruse at a lower speed and enjoy the fuel economy and know that IF you do need to go faster for any reason, you have the ability...problem solved! :D
 

mpsyamaha

Petty Officer 1st Class
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Jun 8, 2007
Messages
395
Re: How much HP for my 17 Glasstream bass boat?

If you are serious about saving any real amount of fuel long term, going to a new technology engine is the only real choice. But, as stated before, it takes a lot of gas to equal the price of a new four stroke or DFI 2 stroke. Either one, in 115hp, would be a noticeable decrease in fuel consumption at anything from idle to cruising speeds when compared to your 6 cyl beast.
 

btbowhunter

Recruit
Joined
Mar 24, 2011
Messages
4
Re: How much HP for my 17 Glasstream bass boat?

Thanks to all for your responses.

All were helpful and made sense. Guess I'll stick with my old motor for now till something major presents itself and then consider the benefits of newer technology
 
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