Modifying old Javelin hull

[cep32 5]

I've got an old Javelin that is pretty narrow at the transom and has a lot of rocker. With me being 120kg and my crew being 80kg we find that it's almost impossible to get the transom up out of the water and, until we get planing, we dig a really deep hole in the water.

 

Is it feasible to cut the seams of the hull from the transom to some point forward and reshape the hull? It seems a pity to give up on the boat when all the other systems work well and there's all that material there that could be reused. The hull is glass over ply without a false floor.

 

Has anyone done this and was it worth it?

 

Just for clarity, I was thinking of running the chines parallel to each other back from the widest point and removing 50-100mm of rocker from behind the widest point back to the transom. I'm not too fussed about the boat being competitive as it's pretty old and if we race it's on handicap anyway.

[Frank 203]

I'll ask my brother in law he pretty clever at that sort of thing 

[cep32 5]

Thanks.

[Frank 203]

On 19/11/2025 at 10:28 AM, cep32 said:

Thanks.

I talked to my mate, he says is its doable but fair to say he was less than enthusiastic he advised you would want to do some back of an envelope calcs and modelling to see if you are too far into the diminishing returns trap. By way of example say for argument's sake that a combined crew weight of 160 kg would make the boat more competitive, so you are looking to gain 40 litres of extra volume  but you will add weight with the extra skin and structure etc so call it 50 litres visualised thats 5 x 10 litre paint buckets side by side, that's a lot . You will be calculating the volume of the prisms created by long triangular shaped inserts which is tedious but doable since its all triangles. Before that get some corrugated cardboard or balsa etc and build a scale model  and then play with that to determine what's possible, this can also be done in CAD or a hull design program if you have those skills or access to them, do all of this before you cut into a perfectly sound hull .

Overall his opinion is that you would be better to swap your way into a more modern Javelin  or another bigger design that is more suitable for your situation,(Ross 490 or flying dutchman etc),  particularly if you are mixed fleet racing or just enjoy fanging about and having a good time. The good gear should be transferable to a later model Javelin like the ones with a false floor and much  of it would also be transferable onto a different class design.

I have glossed over the tricky process of scarphing in those long triangular inserts, modifying the keel/skeg and a new transom  all while trying to keep the additional weight down.

I Hope this helps 

 

[cep32 5]

Hi Frank,

That is a very helpful reality check. Especially the warning that I might end up ruining a perfectly good hull. I'll do some calls and see where I get to.

Part of the issue is that being in the south island, all the newer Javelins are a very expensive ferry ride away so it isn't often worth relocating them.

The only false floor one I've sailed had a very light floor that I was worried I would put a foot through. Maybe strengthening a false floor would be a better use of my time.

Thanks again for your response.

[Bad Kitty 341]

Yeah I'm renowned for poorly planned projects that run over time & over budget but even I felt nervous reading the first post! (Please take this in the good humour it is intended.)

[cep32 5]

I'm all for poorly planned out projects but it's great to have the knowledge of people here to highlight the risks. 

Laying at night awake in the early hours puzzling is normally a good indication I need to ask for help.

[mattm 107]

I haven’t seen many of the newer (post 1980?) Jav’s up for sale in a while, what is the state of the class now? There is a pretty cool classic called ‘Fantasy’ on Facebook marketplace at the moment though  

I just had a Mistral relocated from Auckland to Picton with South Island Couriers. Was on a beach trailer on top of its own road trailer, that came on the transporters own trailer. $900. Was worth every cent vrs. ferry, fuel, mileage and my time to drive and get it myself.