How much power do I need?

[wca_tim]

Re: How much power do I need?

I had an 18 bow rider with a very healty 4.3 in it and it would run close to 60 propped right and loaded light, it would pull 50 and have a decent holeshot loaded and had a decent hole shot and was fine to pull skiers that way. now the same boat has ca 450 hp and fully loaded cab pull a big skier out on a slalom ski at half throttle...

I would say you'd be happy with a 4.3 in a smaller, light, shallov 18 ft hull, much bigger than that and anything smaller than a 5.7 is going to feel anemic when the boat is loaded. for anything over 20 ish feet - especially if a little deeper, heavier hull made to handle bigger water, I'd want a big block...

just my two cents... but then again, what do I know, my daily driver is a somewhat modified ls engine corvette... I drive it for the fuel economy

 

[RL Gman]

Re: How much power do I need?

Funny RL Gman, but I did the "more power" thing for years, and now I'm going the other way: my boat is the smallest horsepower engine I've ever had, my cars keep getting less power, even my motorcycles are getting less (and slower)....must be my age is showing!!!!

I'm still climbing that mountain, but will soon reach the top...I'll probably follow a very similiar trend on the way back down...

 

[jkust]

Re: How much power do I need?

I have the typical, cliche 18 foot open bow. It is rated to 270hp but I only have the 190hp v6. The boat excluding trailer is a hair under 3000lbs dry weight so wet with 33 gallons of gas, gear, two adults and two little kids, it is heavy. I will say the first time I had 4 adults and my two little kids, I was a little embarased at how poorly it got out of the hole. It would have been even worse had I been towing someone. With just the four of us you'd never know it is anything but adequate but just two more adults and it is evident why the offered a v8. My point then is I have never said boy I wish I had even less hp and less torque but I have said on many occasions that I wished I had 80 more horses and a whole lot more torque (i.e. the 270 hp v8). Lastly, you can't compare an outboard to an I/O like someone did up top. There are just too many factors that skew the comparison so of course much lower hp outboards will outperform higher hp and heavier I/O's. I have a similar sized bowrider with a much lower horse OB and they perform much better on much less hp. Lastly, I will just say that the v6 equipped boat is a much easier resale than the 4 cylinder if you care to look that far ahead. The problem is it is hard to find the v8 equipped sub 20 foot, newer bowrider. Many aren't rated for a v8 or even if they are few upgraded to it. I held out for the perfect used boat until I realized I'd have to order it new.

 

[Mark42]

Re: How much power do I need?

If you are not satisfied with the hp of the boat you get, there is always the option of changing props and adding trim tabs. In fact, if you want to go out loaded and tow one day, and go out light and fish the next, you should have two props. One to get on plane fast, and one for high speed/cruising economy. Takes all of a couple minutes to change the prop. Especially if you do it often and things don't get all corroded up.

 

[sleeper]

Re: How much power do I need?

I have a relatively light 19' bowrider with the 190hp 4.3 engine and we do watersports all day long with 4-6 people on board. (a few times with 7 people on board) It works great, and we are large people. Smart tabs and a 4-blade stainless prop totally transformed the boat as well. I think a 4.3 in a 18-19' bowrider is fine. Any bigger or heavier and you want a V8.

 

[hostage]

Re: How much power do I need?

Thanks for all the replies, the more I dig deeper into the more information I find. I am going to conclude that most important factor is power to weight ratio. I see the boats weight can be a big factor. I looked at both a 19ft and a 20ft boat they weighed about 2800 lbs. I looked at a different 19ft boat and it only weighs 2100 dry. They all have the same engine 4.3L V6 Merc. The hulls look fairly similar in design so I am speculating the lighter boat with the same engine should theoretically be able to have an easier time pulling people and carrying people.

So with about 30 gallons of gas x 8 pounds (pint is a pound a world around): 240 lbs of fuel

240 lbs of Fuel
600lbs of People
100lbs of Gear
---------------
940 lbs of Weight added to the boat

Well I guess the question I need to know now is for boats is why do similar size boats with the same engine can weigh 25% more, though that is for another forum topic.

 

[RL Gman]

Re: How much power do I need?

Thanks for all the replies, the more I dig deeper into the more information I find. I am going to conclude that most important factor is power to weight ratio. I see the boats weight can be a big factor. I looked at both a 19ft and a 20ft boat they weighed about 2800 lbs. I looked at a different 19ft boat and it only weighs 2100 dry. They all have the same engine 4.3L V6 Merc. The hulls look fairly similar in design so I am speculating the lighter boat with the same engine should theoretically be able to have an easier time pulling people and carrying people.

So with about 30 gallons of gas x 8 pounds (pint is a pound a world around): 240 lbs of fuel

240 lbs of Fuel
600lbs of People
100lbs of Gear
---------------
940 lbs of Weight added to the boat

Well I guess the question I need to know now is for boats is why do similar size boats with the same engine can weigh 25% more, though that is for another forum topic.

I would be careful to choose a boat based on the fact that it weighs less than an equivelent boat, and because they have the same HP I'll go faster etc etc.

Although, at times that would be correct, the weight of a boat my give some indications to other things. Heavy "new boats" may be made better/stronger. Heavy "old boats" may be waterlogged. etc etc etc...

Depending on hull designs, props, tabs, a heavy boat could preform just as well as a lighter boat with the same engine.

I may be a little premature though, perhaps I should wait for this next topic

 

[jkust]

Re: How much power do I need?

I would be careful to choose a boat based on the fact that it weighs less than an equivelent boat, and because they have the same HP I'll go faster etc etc.

Although, at times that would be correct, the weight of a boat my give some indications to other things. Heavy "new boats" may be made better/stronger. Heavy "old boats" may be waterlogged. etc etc etc...

Depending on hull designs, props, tabs, a heavy boat could preform just as well as a lighter boat with the same engine.

I may be a little premature though, perhaps I should wait for this next topic

There is a reason why some boats of the same LOA are heavier than others. They don't just throw bricks in the bildge to add say 600 or 700 lbs. Make a chart of the available bowriders all the same loa excluding the swim platform length with the same power. Start with premium brands at the top all the way down to the entry level brands (this would be for contempory boats). By in large you will see bigger dry weight numbers at the top and lighter at the bottom. You may very well give up some top end speed with the heavy boat but what you make up for in ride will more than make up for those few times you are squeeking out an extra 3mph with the lighter boat. It is hard to ignore the pattern that premium boats are heavier. Also take a look at the length of the very back/bottom of the hull. Does the hull go all the way back or does it actually end several inches before. For some models (being very general) you can have a 20 foot boat with only as much fiberglass in the water as an 18 footer. This isn't necessarily an indication of a premium boat but just an observation of hull design. Some brands have marketed that you get all the fiberglass you paid for.