Vee hull features.

[paulwilliams]

Given that I am the builder and drawer of my plans take from photos of DF hulls I would say that the hook is not a design inclusion.
However if there are a lot DV hull sthat have a "hook" and go well then it will stay.

Do I need a really flat bottom surface (each side of the keel) or is a mild depression / hook allowable.
I can assume that the keel must be dead straight/flat , no hook or depression allowed here ?

How may it bugger the handling ?
I am new to fast monos, riggers are more my game, cats too.

This should be a very good discussion....I hope.

Simon,

Let me make it clear I'm no expert on monohulls either - outriggers are more my thing too.

Generally speaking, the starting point for setting up a monohull is a straight, flat bottom, with no hook or rocker. However, in order to correct torque roll, it is possible to modify the shape of the hull, for example to add wedges to the right hand side, or to introduce a very, very subtle hook with a thin layer of filler.

The monos I've played around with recently have all been stepped, and these behave quite differently to a boat without steps - usually they're much more nervous and don't turn as well.

Hook/hollows is usually considered a bad thing because it acts like a big trim tab, forcing the nose down and making the boat run very wet, and therefore killing speed - unless the designer of the boat has purposely hooked the bottom to avoid using trim tabs.

I would suggest that the logical course of action is to start with a flat, straight "neutral" hull and proceed from there. If you have very bad torque roll/prop walking, try correcting these with adjustments to the drive angle and by biasing the weight to the left. If this doesn't work, then think about re-profiling the hull bottom, or perhaps running spray rails on the right only, or reducing the spray rails on the left to alter the lift on each side.

When evaluating another design that has hook, you would need to know whether the hook is a consequence of poor quality manufacture, or a deliberate design feature. A badly made hull that works well is pure luck.

Paul

[EPower]

Given that I am the builder and drawer of my plans take from photos of DF hulls I would say that the hook is not a design inclusion.
However if there are a lot DV hull sthat have a "hook" and go well then it will stay.

Do I need a really flat bottom surface (each side of the keel) or is a mild depression / hook allowable.
I can assume that the keel must be dead straight/flat , no hook or depression allowed here ?

How may it bugger the handling ?
I am new to fast monos, riggers are more my game, cats too.

This should be a very good discussion....I hope.

From my understanding Seaducer monos have a slight hook in the keel, i just looked at both my Mhz hull and they have no hook whatsoever

[Simon.O.]

I'd say it's good if the designer intended it to be there, and bad if not, and especially bad if it buggers the handling.

Paul

Given that I am the builder and drawer of my plans take from photos of DF hulls I would say that the hook is not a design inclusion.
However if there are a lot DV hull sthat have a "hook" and go well then it will stay.

Do I need a really flat bottom surface (each side of the keel) or is a mild depression / hook allowable.
I can assume that the keel must be dead straight/flat , no hook or depression allowed here ?

How may it bugger the handling ?
I am new to fast monos, riggers are more my game, cats too.

This should be a very good discussion....I hope.

[paulwilliams]

There is slight hook in the bottom in that when placed on a flat surface the transom touches and about 10" froward touches. There is a slight hollow between. I believe this is a common feature on many of the produced hulls such as the DF.
Is it good bad or otherwise ?

I'd say it's good if the designer intended it to be there, and bad if not, and especially bad if it buggers the handling.

Paul

[sean450]

Simon.O.
From what I have seen you don't need spray rails on the boat. Some boats like my Muck mono doesn't have any on the bottom of the hull like in your illustration.
The spray rails for this hull is actually the overlap of the deck and freeboard. You will have to run the boat to see if water wants to climb the free board and wet down the deck.If it does, add some rails.

[Simon.O.]

I have a 30" DV (22deg deadrise) on the build.
The sides are on and bottom is skinned. Foredeck is framed and will be skinned tomorrow.

Bottom hook
There is slight hook in the bottom in that when placed on a flat surface the transom touches and about 10" froward touches. There is a slight hollow between. I believe this is a common feature on many of the produced hulls such as the DF.
Is it good bad or otherwise ?
I have enough skin thickness to be able to sand most of it out if it has to go.

Spray rails
Attached is a sketch of two different spray rails I have seen.
I will initially build and finish the hull with out any rails.

If I fit rails then is there a preference for either of the two I have drawn ?
Do rails have to go all the way to the bow?

That will do for now. I am sure I will have more questions later.

Thanks.