24' Cuddy + (Re)Design = A DIY Sports Coupe?!

How readily could one add a “pilot-house” to a sports-cruiser of ~24’ in length? The aim would be something that keeps rain out and can be sealed enough to be heat-able. A sort of DIY Sports Coupe in the style of a Regal 35, built onto the body of a [something with a cuddy]. That doesn't cost $150K.

Clearly weight and windage would be key parameters. Thinking in ball-park terms, it seems like it might be viable if the weight were under ~150KG – lower the number and its location the better – and the height less than an additional ~1 metre….

This might be achieved using a new (higher) piece of plastic (Polymethyl methacrylate?) for the windscreen, with the roof and sides made from foam-filled GRP board?

(Driving around under a canvas/PVC tent doesn’t appeal.)

Having not been on any 24' sports boats recently I don’t have a sense of the built-height between the floor plate and the top of the windscreen, and thus how much would need to be added.

Conceivable? Achievable (without becoming one of life’s great undertakings)? Fully stupid?

Appreciate that details will be key as to what would be the most suitable base, but any initial thoughts very welcome - but be gentle!

[Optional reading: background!

I am based in the UK (South-West) and, over recent years especially, the default boat for the sort of thing I do has become a Merry Fisher of ~20’ length. Whilst these are clearly a sensible/mainstream/conventional choice – not least, because they have outboards happy to endure saltwater – I can’t shake a feeling that the Deep Vee hulls from companies like Chaparral, Regal, and Cranchi are ultimately more seaworthy. And, thanks to their having big Detroit engines, much faster. This set me wondering about doing a custom-mod on one to meet a few specific criteria....]

 

Depends.

Placing a superstructure must not affect the center of mass versus the design.

 

Fallguy makes a great point.
Why not build a 150 kg plywood object, put it on a 1 metre pole, and go and test the performance.
Either that, or pay an NA for the calcs.

 

It can vary the longitudinal position and, therefore, the trimming and, therefore, it can force to change the shapes. It can also change the height of the CoG and therefore the stability will be affected and therefore can force you to change shapes.
I don't want to say that it does, I just want to suggest that it can change the design.

 

The concern is moving the CoM forward while the hull remains the same.

I understand your comment, but the hull shape will not change and a cabin forward generally moves the CoM, so people can have fanciful ideas about forward cabins and end up with a boat that won't perform.