How much is too much in regards to HP?

[Drb007]

As we are restoring my daughter's 15 ft Steury runabout, I am shopping around for engines. It came with a 60hp Sportfour. The boat is rated for 70hp. I am chasing a 75hp Starflite, and today found an 85hp Evinrude with power trim/tilt. I have looked for a year for power trim/tilt to fit the Sportfour with no luck. So if going with a slightly newer Evinrude (hate to give up that cool style of the older ones) means she can have trim/tilt, maybe its worth it.
The question is: is 85hp too much for that boat? I know it's 15hp more than rated, but I am reading that that has more to do with weight than anything. We are putting in a new transom on her boat, still debating wood or SeaCast.

Thoughts?

 

[Woodonglass]

My boat was rated for 70hp and I put a 85 hp Johnson on her. She does just fine with it. I Don't run her WOT most of the time!!! But when I do, she still does just fine. Weight was not an issue either. I WISH mine had T&T but alas it does not. But, once I found the right setting I'm finding that I don't need to adjust her much. If you're getting a good deal on the 85, I'd go with it. Finding a good 70hp motor was a hard proposition for me.:grumpy: I will say that grossly overpowering a boat is not advisable but I don't think this is the case in this instance. Insurance can be affected by overpowering so there is that to take into consideration as well. I felt that I would be safe and my passengers would be too. It will be a decision you will need to make taking all the factors under consideration.

Others may come along and disagree with my point of view!!!:noidea:

 

[gm280]

Drb007, if it were my boat setup and that was a good deal, I know I would use it. But like WOG stated, insurance could be a sticky point. Even though I think it is not that big or over sized, your insurance can easily use that to not pay if anything happened. So you have to make the ultimate decision and live with it. You could talk with your insurance agency and tell them about it and see what they would say. I mean if they agree with the engine, then get it in writing and happy boating. Mind you, this is just my opinion and has nothing to do with iboats. Because we would never tell anybody to install any engine above the max specified. But there is nothing saying the capacity plate can't be replaced. IDK :noidea:

 

[DeepBlue2010]

The weight issue is not linear as you might think. In other words, if you have 60HP engine weights 100lb, a 41% increase in the HP to make it 85HP will not increase the weight to 141lb. Actually you can gain that much HO without any weight added at all.

Your relatively newer 85HP engine will be almost as heavy as the old one if not lighter because of the modern fabrication technology. Long story short, I don’t think the weight is an issue. From a power stand point, you are not going from 100 HP to 200HP or anything. It is only a slight increase that if you don’t go crazy on the throttle, you might not even use it or realize it. I would say go for it.

 

[Drb007]

I assume the weight of all three engine choices will be similar enough to not make a huge difference, and I would hope we do a solid enough job of the transom that it can hold an extra 15 hp. The trim/tilt is what really has my attention.
The hard part is we both really like the curves/style of the Sportfour and Starflite. The 85 seems boring.

As for insurance, at this point there is nothing on the boat that says max HP is 70. That's something I found the original sales brochure that I have. The tag where it should say it is buggered up from a bolt for a kicker motor that lived there at one time. So who's to say the new sticker won't have an 8 and a 5 on it?

 

[Cat nip]

No such thing as too much horse power! If the boat wont sink sitting still it will be fine. Ya do t Hafta go WOT if ya do t want to but when ya do it will be a nice improvement.

 

[DeepBlue2010]

No such thing as too much horse power! If the boat wont sink sitting still it will be fine. Ya do t Hafta go WOT if ya do t want to but when ya do it will be a nice improvement.

This is inaccurate statement. While the boat might not sink sitting still, it can sink going vertical under the forces of thrust power that is way too much for its weight and load capacity. It is like putting a plane in a stall with the same disastrous results. In the situation the original poster is describing it might not be an issue but to generalize in a statement like ?"No such thing as too much horse power" is simply not true.

 

[Cat nip]

To each there own. Either you like pushing the limits or ya dont. To me, it ain't fun till you pucker up! I put twin 35 hp tillers on a 1953 16' aluminum fishing boat that was rated for 30hp. Had a hole shot like you wouldn't believe and went like hell. It was reckless and fun and we lived to tell about it. If it doesn't feel right to you then don't do it.

 

[Watermann]

What year is the 85 HP? There could be more of HP differnece than expected if it's new enough to have a prop rated HP over the recommended flywheel 70 HP from the manufacturer.

 

[Drb007]

Let's all remember this is going on a boat for my 16 yo daughter. I'm looking for safe, reliable and useful. It's the power trim/tilt that is drawing me to the bigger motor.

 

[DeepBlue2010]

To each there own. Either you like pushing the limits or ya dont. To me, it ain't fun till you pucker up! I put twin 35 hp tillers on a 1953 16' aluminum fishing boat that was rated for 30hp. Had a hole shot like you wouldn't believe and went like hell. It was reckless and fun and we lived to tell about it. If it doesn't feel right to you then don't do it.

I don?t assume the original poster was asking us to define the acceptable level of thrill for his little girl or the right amount of adrenaline that we deem acceptable for her. I assume he was asking about what is most appropriate for her safety. Next time when you answer a questions like this, don?t make generalized statements if you meant o talk about your own personal standards. Start your post saying something like (For me, there is no such a thing as? ) or ?I am the type of guy who like to flirt with the angel of death) to avoid misleading people into believing that your personal style is the right way of doing things.

 

[jbcurt00]

Let's all remember this is going on a boat for my 16 yo daughter. I'm looking for safe, reliable and useful. It's the power trim/tilt that is drawing me to the bigger motor.

Lets try to focus on what DRB is asking ^^^

Do I think you will have any problems going w the 85? No.

Do I think its wise to overpower a boat? No, esp not for a teenager.

Will I recommend it? Nope.

Have I done stuff that MIGHT have proven less then smart? Yep, we all have. Doesnt mean I'd encourage others to repeat my foils...

Bottom line is only YOU know your daughter, the boat, what you've done to it and what it needs done from here out.

IMO, theres boat work to be done, and until its finished, it doesnt really need a motor. A 70/75 3cylinder Johnson/Evinrude would be ideal.

It the 85hp is a good deal, buy it and clean it up over the winter. Then sell it in the spring to fund a different outboard that has T and T but fits the limits of the boat.

If you or any of the other iboats members can find the capacity rating for your boat, in the event of an incident, I'd expect that information to be found by anyone looking regardless of whatever tag you create to change the 70hp rating to 85hp.

In WV, overpowering is prohibited expressly in the boating regs and also prohibited under maintain safe operation at all times regulation. Many states have similar safe operation regs that may cover overpowering too.

Lastly, I suspect your daughter will make a few mistakes as she moves from childhood to being an adult. IMO, choosing to overpower the boat and modify the capacity rating isnt something I'd want to teach her as acceptable from a responsible boat owner or operator.

 

[Drb007]

jbcurt, thanks for getting us back on track. I certainly appreciate your warnings about overpowering the boat. However, I would argue that going from a 60 to a 75 or even to an 85 is an unsafe jump. I can adjust top speed with a prop change that would keep her in a safe range. I don't think it is irresponsible to think this matter through in the process of rebuilding a boat and putting 15 more hp than it is rated for. 50? 100? yes, that would be serious. But I am not out to deceive the DNR, a future buyer, etc.

That being said, if she can get a solid running motor with power trim and tilt, I may jump on it. If we can't get that one, then it will likely be the 75 for now.

 

[jbcurt00]

For reference, you think the 85 is a 1973 motor, correct?

Then it too is crank rated, like the other 2 motors, and matches the time period the boat was built and spec'd for a 70hp.

Thinking it through is great and my point was really just to give you more to consider.

You expressed the desire to go the safe and reliable route and I agree w that plan.