Welding a boat?

I have been trying to build my own boats. But they keep falling apart, what is the best way to weld the parts.

There are many plug-ins you can use to do easy welding, I use Ozzypigs Weld Plugin to save time, however if you want to do it manually and with more precision I'd recommend creating a script that iterates through all of the parts in your model and welds them to the primary part of the model or just a random part. You can find examples of scripts to use by just looking at a ROBLOX recommended model that uses buildings and that can help you make one. You can also find a simple one. I hope I've helped you in any way. If you need a script example posted here I'll put one up.