I grew up water skiing behind your typical family production boat. I also have several seasons at Havasu on a friend’s 21’ Shockwave. My wife and I recently purchased our first boat a 2004 25’ shockwave with a 500efi.

Is there a top speed/engine power for a boat like mine? As I understand from my boater safety course most production boats have a max recommended engine size.

As I learn more I have heard/read of guys supercharging there engines or putting massive 1000hp motors in boats like mine or even smaller boat.

The reason I ask is, at 78mph (indicated on my speedometer) my boat was starting to get a little “floaty” for lack of a better term. I was wondering how a boat can handle such a jump in power without just becoming a youtube crash video.

Sounds like chine walking. When you're running with very little wetted surface, your boat is probably riding on just a small pad, and can "slip" from side to side as it falls off the "pad", which is the the lowest/flattest part of your hull.

that is what I figured,

Can this be corrected? I am guessing it is a trimming issue?

How would a boat with more power not just make the problem worse?

your trim would have nothing to do with it your trim control up and down motion theres really nothing u could do about it

Bad advice, Does it have hydraulic steering? if it does not that will be the first thing to do above 75 mph. A different prop etc. There are lots of place out that way that have experience with that hull and they can probably calm it down.

All boats get a litte "floaty" at speed. Thats when the hull lifts up and starts to release. Chine walk is a definite oscillation from side to side, almost a wham, wham, wham when really bad. You may just be experiencing the wetted surface releasing. Do you have tabs? A performance boaters course will give you the Non "internet opinions" to identify your issue. It may be nothing, it may be something

It has hydraulic steering and Dana trim tabs. I am not really worried about my boat. I am happy with the performance and handling. The floatyness I described is what I expected when running at top speed, and was only felt the last mph or two gained. At 75 the boat felt solid. My question is, with more HP's, different prop ect, the boat will go faster. Please correct me if I am wrong, as the boat goes faster, it will ride higher in the water and things like chine walking ect would become more evident. How do people with boats my size and smaller safely put close to 1000hp into their boat, increase speeds close to 100mph and not have issues?

There is no way to put a 1000 hp in a 25 foot v-hull boat and say theres anything guaranteed when it comes to safety, gimbal breaks or you hit a wave wrong at 100 mph its not going to be pretty. I will say however, my 272 Baja runs 100mph, I have added longer trim tabs and full hyd steering, driven right by someone experienced it is super predictable to low 90's, it feels more solid at 80 than my buddys NON hyd steering Checkmate does at 70. Above 92-95 depending on the load, it is aired right out and on the edge of something very bad happening. Your boat would probably benefit from twin ram FULL hyd steering, it is night and day different, Smitty

Artic Thanks for the reply.

I am not really worried about my boat. I was just wondering how it is possible.

I did have someone explain it to me this way:

The boat gets "floaty" as it nears its top speed because you have the boat in its lowest drag settings in the water, this includes trim tabs and drive. In a boat with more power the boat will reach a higher speed with the trim tabs and drive still in the water. Then just like at the lower speed with less power, as you raise the trim tabs and trim the drive to maximise efficiency and lowering drag the boat will start to feal "floaty". So in theory the more power/speed is not the main factor in the "floatyness" it is how much boat/drive/trim tabs you have in the water.

Does this sound correct or is it way off???

This is my take on the subject...all hull designs exhibit different characteristics at higher speeds.The less wetted surface you have the less resistance there is to move forward thru the water or over the surface of the water. Applying more power to overcome this resistance reveals limitations in the design relative to adhesion to the surface of the water.

External mechanics such as trim tabs, external hydraulic steering, different prop designs,etc.tend to correct the shortcomings in any particular design relative to safety and handling at high speed.

That being said and to answer your question, many boaters (such as myself) boost the available power not necessarily to achieve a higher top speed but to improve the overall enjoyment of the boat. With big power available acceleration and load carrying ability as well as cruise speed are enhanced. I know with my old 255 Formula going from 500 to 800 horsepower in the water makes it a hell of a lot more fun to drive under all conditions as well as pushing the top end quite a bit.