Lengthening a sailboat

[yorktownie]

I have a Yorktown 35 aft cockpit fiberglass sailboat. I have lived aboard it for 12 years. It is fairly well equipped and in good working order. I took it to Mexico for a season in 1998. Now I have the desire to install a pilothouse and aft cabin.
I asked Sam Devlin (Seattle boat desgner/builder and stitch and glue guru) if it could be done and if so would he draw up the plans. I would do the work. He replied that it could be done, but he hoped I was very much in love with the Yorktown to undertake such a task. My experienced builder friends also tell me it is a great deal of work to lengthen a boat. I would say I like my boat, I am certainly not in love with it. It is just a question of economics. It would cost at least 50K to sell my boat and upgrade to a 40-45 foot boat with a pilothouse and aft cabin. Also, I would probably have to invest in the new boat, since it would probably need work. At least the Yorktown is a known evil, and there are no hidden money pits. I want the pilothouse and aft cabin to be strong and look good. They must be watertight and the boat must handle as well as it does now, or at least nearly as well. Yorktown made 35, 39 and 41 foot aft cabin, center cockpit models. I would need to move the steering pedestal 2 feet forward and remove the fore and aft cockpit benches, then add 4 feet or so to the length aft. Can somebody briefly outline the process of lengthening a fiberglass hull so I can understand why it is such a tremendous undertaking?

[Eric Sponberg]

Yorktownie,

I checked on the internet to get a picture of a Yorktown 35--which is a transom hull with an aft cockpit. Cockpit shape is fairly simple--no complicated contours. The simplest way to extend the hull aft is to do a fair extension of the hull lines. Cut off the back of the deck through the cockpit and throw that away, and rebuild the deck with the aft cabin and accommodation inside. The cockpit will likely be shorter so that you can use some of the room close aft of the deck cut for the berths in the aft cabin. You would likely gain a lazarette area behind the cabin for storage.

All this involves labor hours and care to get the shapes of the hull and deck house right. The cost will be whatever it takes, and a few builders might give you some ballpark ideas before you commit to hiring a designer to do design and structural drawings.

Some other things to think about: In a fair extension like this, the added hull length and accommodation are going to be right at the aft end of the existing waterplane, and most of that weight will extend aft of there with little to no additional submerged volume in the hull to support that weight. The boat is going to trim by the stern. To compensate, therefore, the faired hull extension should actually start behind the keel so that you can pick up submerged volume to support the extra weight. You will lose a lot more hull that will have to be replaced deeper down. That's a lot more work.

Also, The rudder, in proportion, will be too far forward and maybe too small. So the rudder and steering system will have to be redesigned, rebuilt, and positioned further aft. That's more complication and more cost.

Those are some of the factors that will go into such an extension.

I hope that helps.

Eric

[alan white]

It's about as practical as enlarging your home by 6 inches in every dimension and a good reason to get excited about a new used boat that's bigger already.
In addition, there's a lot of talent involved in both design and building. If you do the work yourself, you will have to be a very good designer/craftsman. If not done well, the boat might be almost worthless to any future buyer.
Those are realities, but if you already are aware of them, go for it.

[yorktownie]

Yes, failure is not an option. The thing is, I will never get my money back out of the boat anyway. Yorktowns have low resale value, even pristine, well maintained and improved ones. I could not get more than 20K for my boat and have put at least 65K into it. I had not considered moving the rudder, and it might not be necessary. The boat has a 'fine' clipper bow. There is a 40 gallon water tank under the Vberth and the sailing performance is noticably affected when the tank is full - it can slow the boat down by a knot or more. I would think the added weight on the stern would keep the bow up a bit, and some of the fair extension would be in the water and add buoyancy. The rudder post is currently only 2 feet forward of the transom, about 1 foot aft of the cockpit deck. I don't care much about racing, only safety and comfort. Removing the entire cockpit deck and seats was not something I had planned on. That would complicate the job. I am beginning to see the magnitude of the job. I had envisioned a few main parts:
1) Remove fore and aft cockpit seats.
2) Move steering pedestal forward (not rudder post - it's rack and pinion).
3) Mount pilothouse support posts.
4) Cut off transom, embed stringers all around hull extending aft.
5) Add sides, top and windows around this framework.
6) Fair and finish.

Something like that.

[RHP]

You´re a brave man, I expect 99.9% of members of this forum would choose to purchase a larger boat - by doing extensive research you could minimise the price difference which would be recooped at time of eventual resale.

[PAR]

From a sailing lines and balance point of view, Eric is right, your best bet is to hack off the boat at the aft end of the keel, probably taking that little piece of fairbody with it. This means you'll lop off the last 1/3 of the boat and have to engineer a new, burdensome stern quarters. With so much additional hull added, you'll surely need a new rudder and hopefully the new aft quarters will offer some additional bearing area to support the bulk of the addition.

The cost of a project like this will rival the purchase of another larger, used boat. It sounds like you want a 38 to 40' boat, like a Morgan Out Island 39'. You can find these in abundance in every condition. With the current market, deals are everywhere. You can find a fairly well dressed example with a desperate owner.

[yorktownie]

I am convinced. Chances are I would end up sailing in a fairly nice looking boat with a miner's shack tacked onto the stern, which the first gale would likely sweep away. I thank you all for the input. I really do want a larger boat.