Outboard power?!

[thetackletrap]

Is it true that when considering powering your boat with outboards that you are suppose to use at least 80% of the maximum rated transem strength. For example, I was told, that if you have a boat with the maximum transom hourse power of 100hp then the minimum power required is 80hp. I actually think you should be closer to maximum hp, unless it is just a super over built boat where the max hp is just something insane. I also feel that if you are near the max Hp that the resale of the boat is higher and better.

Now there are alot of variable here to consider. One is the weight of the motor. Your boat may be designed for 400 hp, and that rating came about before 4stroke technology. So if you plan on repowering your boat with 4 strokes then it may be too much transom weight making the boat sag in the arse end therefore you have to go with new 2 strokes of smaller 4 strokes.
Another variable here to consider is the amount of ffuel consumption. If the boat is powered at 80% of maximum hp than the motors will work harder than if at 100% I would think that this is actualy creating worse fuel mileage, because you have to run the motor(s) harder than if you had more power. This I believe to hold very true if you are compairing twin or triple motor boats. But what about that switch of going from a single to a twin? Say your boat has a max of 300 horse power. Curently you run a single 250 and you average 2mpg. Now you want to upgrade to a new engine. Would you want to get a single 300 that you will get 2.5 mpg or go to twin 150 where you could get 3mpg but you have to times that by two? So you see that there is alot to consider here. Plus you are dealing with buying to engines instead of oine but on the other hand you have a more reliable source of power with twins.
So I guess there is alot more variables here then just buying at least 80% of your boat power here. All I know is that it is an expensive venture and that just adding more power isn't just to go faster. Actually adding a second motor or adding more power by buying two bigger ones can slow down a boat because you have more drag and weight!

[Lil' Tunny]

Think I lost you about 3/4 the way through. They max horse rating isn't determined just by how much weight and pressure the transom can support. It's a munber of things based on the hull design. I believe the CG actually determines what the max rating is on every make and model hull?
The best thing is to get as close to the max as possible. When it comes to resale people don't want a boat that is, or they think is underpowered.
I think the only disadvatage of twins is the added cost. The initial purchase and having to maintain 2 motors. 2 motors don't seem to burn that much more fuel than a larger single.
Have you noticed the MPG's for the Reg w/twin vs the kennycraft w/single?

[thetackletrap]

Originally Posted by Lil' Tunny

Think I lost you about 3/4 the way through. They max horse rating isn't determined just by how much weight and pressure the transom can support. It's a munber of things based on the hull design. I believe the CG actually determines what the max rating is on every make and model hull?
The best thing is to get as close to the max as possible. When it comes to resale people don't want a boat that is, or they think is underpowered.
I think the only disadvatage of twins is the added cost. The initial purchase and having to maintain 2 motors. 2 motors don't seem to burn that much more fuel than a larger single.
Have you noticed the MPG's for the Reg w/twin vs the kennycraft w/single?

No I didn't, yeh I kinda got lost threw my post because i kept thinking of things as I was writing. Too long but hey...I think you are right about the coast guard. I believe there is a stamp/ metal plate that says its inspected? Not positive if it is on every boat though. I was up too late last night posting.

[Capt.Mick]

Lil Tunney is correct the rating for HP is based on the recommendation of the CG and the hull design. As far as hanging the HP off the back the more the better, (unless you have a small fuel tank).

-Mick
Barnacles.llc

[Parker21]

I think the 80% of max HP is a good rule for most boats, but there are exceptions like my boat which is a 23' kencraft rated for 500 Hp and mine has a single 250 on it. I don't think it underpowered because I still top out at 46+ mph and can cruse at 32 mph. LT I think that most of the time the single is going to get better fuel econemy than twins, You can't compare those yammis to a merc EFI because those mercs are pigs on gas. I bet if i had a suziki 250 I could get 2.5 mpg instead of 1.2 mpg

[Lil' Tunny]

Originally Posted by Parker21

I think the 80% of max HP is a good rule for most boats, but there are exceptions like my boat which is a 23' kencraft rated for 500 Hp and mine has a single 250 on it. I don't think it underpowered because I still top out at 46+ mph and can cruse at 32 mph. LT I think that most of the time the single is going to get better fuel econemy than twins, You can't compare those yammis to a merc EFI because those mercs are pigs on gas. I bet if i had a suziki 250 I could get 2.5 mpg instead of 1.2 mpg

Ouch! What are we going to do about reserve for the scallop trips? I hope fuel prices drop this year
You missed a super fun day tuesday Check the photos some dude put on the 7 board. I'm in one of them, I was paddling back out, sitting on the shoulder, watching guy get a clean barrel.