Is it possible to make a H14 8' wide by using the mast beam and rear beam from a H16?
they are close to the same---H14 is 7'8", H16 is 7'11" it think.
Yes, the beams will fit perfectly on the 14 pylons and you can use the 14 side bars to connect them. You will have a much larger span between the trampoline pieces running down the center of the tramp.
I have thought about doing it, but I end up with the conclusion that if I wanted to make the boat wider, I might as well go with a Hobie 16. I would be adding extra weight to a boat that doesn't like a lot of weight and it would take a complete set of custom rigging to get the boat going. You would also need a H16 crossbar for the steering system.
To be honest it will work but theres no point. All the bean sizes are the same but the problem will be is you will have a hobie 16 mast bass on it and well the 14 and 16 mast bass are different. If you really wanted to do this i would suggest to buy a hobie 16 and just pull the side beams off and put the 14 beams on and put the hulls on thats what your really looking at!!
Um, but then I'm stuck with a H16 mast on a 14' boat that would be even worse for sailing in heavy weather. I'm looking for a wide 14' boat to single-hand in severe weather.
Besides, who said anything about buying stuff. I'm talking salvage here. There are at least a half-dozen abandoned H14s sitting on the beach, and one complete (well, minus the boom and sails) H14T. It needs new shrouds anyhow, so making longer ones is a moot point. H16 beams and an TheMightyHobie18 tiller (hey look at that abandoned TheMightyHobie18 sitting next to the H14T that hasn't moved in 4 years except when I drain the water out of its delaminating hulls...). My friend was given a H14 all-aluminum mast and new mainsail for free, that I be able to get donated to the cause....
Hey mate
When yiou say sail in severe weather how much wind are we talking about?? I have a feeling you might just pull off putting a 14 mast on the 16 beams it might just take some ..............improvising 
Look at the difference between the cup size of the hobie 16 mast base and if you can swap them around yay but if you cant well this is what you could try. Take the mast bass to someone who can weld and ask them to add extra mettal in and well then you have you mast base. Just a thought!!