20 vs 30 HP 4 stroke

[kokes]

I have a 14'7" Crestliner aluminum boat with a 20 HP Honda. It works great but when I need to get to another location it's a drag as my top speed is 8 MPH at my altitude (5000 ft). The boat is rated for up to 35 HP. I'm wondering if increasing the HP will make any real difference in top speed. Any advice would be appreciated, thanks

 

[roscoe]

Jumping up to a 35 will definitely make a difference.

Then make sure it is properly jetted for the higher elevation, and you have the correct pitch prop.

Or buy an refi motor, and the correct prop..

 

[Sea Rider]

Plan going for a new 35 HP motor, or rejetting and proping right the current 20 HP motor ?

Happy Boating​

 

[RMClark]

I have a 14' Lund with 20 HP Merc; the boat is rated for 35 HP. That motor will push the boat to 23 mph with two fisherman and gear.

No, I'm not running the boat at an elevation of 5000 feet. But, I do think it would go well over 8 mph on a lake at that elevation. There has to be some reason why your boat will only go 8 mph, and I don't think lake elevation is it.

You don't say how long you have ahd the boat, but has it always been this slow?

Far be it from me to tell you not to get more power if you want more power. But, it sounds to me like there's more to your "underpowered" situation than elevation of the lake you're running on. I'd look into the whole setup so that I was sure I knew what problem was being solved before re-powering the boat. Otherwise, you might be disappointed at great expense.

 

[dwco5051]

From my boating experiences I would think your rig should be at least in the18-22 mph range just as RMClark's. I do not know why you are not achieving at least 15. My 14' Crestliner with a 30hp tohatsu 2 stroke and the correct prop will do 30 on smooth water. Before you spend on a another motor I would investigate why you are not getting that now. Wrong prop, engine not tuned right, etc. You should be able to get 8 mph if it is only firing on one cylinder.

 

[Sea Rider]

Answering to Kokes post, If you don't want to expend the extra $$$$ on a 30 HP motor, need to rejet the current carb with high elevation jets if boating above 2400 feet of elevation along a correct prop maximization towards less pitch props for the motor to rev at their max wot rpm range factory stated as usually loaded. Should see a notorious speed improvement. Will need to rejet again the carb and change the prop to previous ones when boating at sea level...

Happy Boating​