boat stretching

I have a 23' x8'-3"outboard powered boat that a guy likes but wants a 25' in my line drawing it appears I can cut and add a two foot section about 2'-3' ahead of the transom, has anyone done this or something like this,, I would like to know how this was done and how it turned out Thanks Bo

 

Hi Brokenshear, This is done routinely up here to fiberglass boats. Every one is an individual and the place to cut changes relative to design. If one looks down a hull, there will seem a point where there is less change or the flare starts to come around to tumblehome and that is often the best point. As far as cutting and stcking back together - no big deal. If you decide to do it, say so, but you are basically going to grind most of the eventual seam before you cut with the sawzall, ready for glass. Stringers are cut in a different place, deck in a differen place. The bottom is cut first and beams are installed under, cut sides, slide aft portion back, lay in unwaxed, new melamine board (you will still be able to seperate but best to keep parting agents away), glass inside, install stringers, remove form where joint is but continue to support shape (even with stringers, I have seen them sag a tiny bit), glass outside.

 

Hi Mark775, I don't think I will have to cut a built hull as I have the mold, and the interior structure would not be in the way I may not have explained that clearly enough but in short my mold is 23' I have a customer who wants a 25'.. Thanks

 

Well, I know Blackman and Westport and some others simply have a longer mold than boat and plug up the back end and start laying up... This doesn't apply to you (plus its not too attractive to have a perfectly flat transom). I think that you would still want to lay up a front and a back and join them. It will be harder to maintain a shape without stringers and bulkheads so I would maintain the designed shape just past the joint area. Tumblehome really complicates things if joined at the wrong spot but two foot extensions are easy to tweak to line up. Another possibility is to pull a boat, screw melamine board to it to make the extension, glass up the extension right to the existing transom, pull mold, make as fair and perfect as you wish, pull a mold off of that, then you have it for the next guy with two-footitis (the temporary male mold won't stick that well to the gelcoat and the screw holes are easily patched)

 

Stretching a hull isn't uncommon even when new. One of my customers that does it frequently almost finishes the boat, so like mark775 said, the hull keeps it's shape during cut and stretch the process.

I have several customers that add from 2 - 4 feet to special ordered boats in this size range, as the boats get bigger the added length is increased.

 

I saw something like this done on a smaller size boat and the way they did it was to cut the hull and with out any stringers and bulkheads attach a bunch of tempory small stringers with screws and glass in the added section, being I have the mold I can make a section to glass in and fair the hull when its secured with the structure any tips?