Stepped hulls pros and cons

[AdrianRO]

HI,

I have built a boat ( see attachement ) and I want to improve the hull by adding a step.

Doaes anyone can light me up about the advantages and the disadvantages of this solution, in order to ba aware of everything when I will start doing it ?

I will be happy with any informations, I have 0 experience about this. Does it has to be bow pointing, stern pointing, or simple straight?

Thanks for the help

[AdrianRO]

This is the picture, actually

[FAST FRED]

A step is built into the hull.

A wedge can be added to a built hull , and helps get the correct bow angle.

With an outboard you can ALREADY trim the bow up or down..

FAST FRED

[AdrianRO]

I have actually the intention of building the step into the mould and release a new version of the hull. I am the builder of the boats, and there is no 'splashing' involved.

The question I am askng myself is that is there any reasonable performance increase worty so I start all the job. Boat does 32 knots with a 90 HP Mercury Optimax, best performance.

On the other side I think we can get ourselves in the situation of wooorking all winter long and get no reasonable result, or even worse, an inpredictible hull in turns.

so. once again. is a 6.20 meters long hull like that going to be improved with a step? I see Rancraft done it on a similar hull, with the vee shaped step, pointing bow, and about 80 mm offset.

[Verytricky]

There appears to be more art than science at the moment. Best advice would be to splash an existing design - but this is both legally and morally wrong. The alternative is months and months of trial and error, or to get someone who does know steps design this for you.

Primarily I believe the step it to gain top end speed, at the expense of some handling.

[Willallison]

For the sort of boat you are talking about, I'd say that the primary reason for incorporating a step is for marketing.
In that regard, it wouldn't matter too much what type you use (within reason, of course!) Take a look at steps on similar boats and try something similar.
If you really want to make a difference, then as VT suggests, go to someone who knows - like Michael Peters, of Ocke Mannerfelt

[Raggi_Thor]

I say this again and again :-)
Most people want to optimize for top speed while they spens more time (and fuel) in lower speeds!
If you add a step you probably need more power but then you can brag about "60 knot top speed", for example :-)

[AdrianRO]

Marketing, indeed, it's the main reason for what I intend to do it, but I would not spend a summer or so to try it until reaching a suitable result. And yes, Thor, who wants to get a top speed might simpl put an overszed engine and will reach the desired top speed. For the rest of them, the 90 HP delivering 32 knots will be acceptable.It is intended for a family boat, afterall who wants his kids to fly off the cockpit while attempting a record...

[Verytricky]

Originally Posted by Willallison

If you really want to make a difference, then as VT suggests, go to someone who knows - like <snip> Ocke Mannerfelt

Originally Posted by Raggi_Thor

I say this again and again
Most people want to optimize for top speed while they spens more time (and fuel) in lower speeds! If you add a step you probably need more power but then you can brag about "60 knot top speed", for example :-)

Then speed is beauty - The faster she is the better looking she is. Ugly is a slow boat.

Originally Posted by AdrianRO

Marketing, indeed, it's the main reason for what I intend to do it, but I would not spend a summer or so to try it until reaching a suitable result.

Perhaps the step is not for your market then? or place a 'fake' step that will not affect the handling?

Originally Posted by AdrianRO

It is intended for a family boat, afterall who wants his kids to fly off the cockpit while attempting a record...

I say nothing....