trendsetter240
Lieutenant
- Joined
- Jun 22, 2009
- Messages
- 1,458
I'm seeking some advice on engine HP, Weight and prop selection to repower my 17ft grew boat.
I'm not certain of the exact year and model, only that it is fiberglass over plywood and is quite heavy (maybe 2000lbs?). The boat has a 20" transom and is a deep V hull.
There is no plate on the boat to show the Max HP rating so I used the (L X W X 2) - 90 formula to come up with 114 as the max HP.
The only outboard that I've been able to test it with was a 50HP Mariner. With the 50 it would plane easily with only me and fuel etc onboard and max out around 22MPH at WOT. With two people it would still plane but only reach about 18MPH. 3 people and gear and it would plow through the water at about 10MPH.
My main concern with a new motor is weight. The newer 4Strokes and DFI engines weigh 50% more than the older 2 strokes. With the 50hp I could stand on the stern and water would be about 3 inches below the scuppers.
My second concern is fuel economy. Using the boat with the 50 I had to keep it at WOT almost all the time to get where I wanted to go and this was burning a lot of gas. 5.5GPH at 22MPH is not a lot of bang for your buck. 5.5GPH at 10MPH is brutal!
The boat will be used for fishing in saltwater within 5 miles of the west coast and in tidal rivers. I'd like to be able to take 3 people plus myself and gear and be able to run about 30MPH between 3500 and 4000RPM. Is this realistic?
What would you recommend for the above scenario, being a safe and efficient setup.
Thanks in advance.
I'm not certain of the exact year and model, only that it is fiberglass over plywood and is quite heavy (maybe 2000lbs?). The boat has a 20" transom and is a deep V hull.
There is no plate on the boat to show the Max HP rating so I used the (L X W X 2) - 90 formula to come up with 114 as the max HP.
The only outboard that I've been able to test it with was a 50HP Mariner. With the 50 it would plane easily with only me and fuel etc onboard and max out around 22MPH at WOT. With two people it would still plane but only reach about 18MPH. 3 people and gear and it would plow through the water at about 10MPH.
My main concern with a new motor is weight. The newer 4Strokes and DFI engines weigh 50% more than the older 2 strokes. With the 50hp I could stand on the stern and water would be about 3 inches below the scuppers.
My second concern is fuel economy. Using the boat with the 50 I had to keep it at WOT almost all the time to get where I wanted to go and this was burning a lot of gas. 5.5GPH at 22MPH is not a lot of bang for your buck. 5.5GPH at 10MPH is brutal!
The boat will be used for fishing in saltwater within 5 miles of the west coast and in tidal rivers. I'd like to be able to take 3 people plus myself and gear and be able to run about 30MPH between 3500 and 4000RPM. Is this realistic?
What would you recommend for the above scenario, being a safe and efficient setup.
Thanks in advance.
