On a boat there are no right angles - only wrong ones. Everything is custom fit with more expensive stainless screws, bolts etc. If you have to mount a piece of hardware on deck, overdrill and fill with thickened epoxy - you won't finish today or maybe the next either as you can't drill & tap the epoxy until it sets completely. A lot is done in cramped spaces (the boat) or worse a part of the boat you have to crawl to. Everything ties into something else or is in the way of something else. Example - redo of my galley. Galley is under bridgedeck so I have to install new traveler on deck before I can close up the interior panel above the galley counter. Of course that takes time as I had to grind around old holes - I moved the traveler aft 8" to better clear dodger that is coming in the future and had to grind & fill a few voids in gelcoat as well. Fill, sand, fill, sand, fairing coat, sand again then paint several coats and finally install traveler. Now I can get back to galley. A lot of the time it's not the hours but the fact that after an hour of work you have to let it dry or wait for epoxy to harden. If it's paint sanding is out for the rest of the day. Estimating time is something I've almost given up on. Then there are the things that have to be custom made.
I think it's very important to enjoy what you're doing. Otherwise you will look for excuses to avoid the job at hand. Never lose sight of the goal. Everything will cost more and take a lot longer than you think. If you're not skilled in the many trades that are required it's a lot tougher. I own my 9th boat now. A CS27 I bought last October. All work has been done in the water. What I most miss is a shop - not so much to put the boat in (that would be nice) but to do the woodwork. I was an apartment dweller when I bought this boat so the boat becomes the workshop as well. Cutting dadoes with a router and clamping the work to a piece of ply in the cockpit slows you down a bit. I'm a bit of a perfectionist as well and that adds time.
I purchased my first sailboat - an old hard chine 18' sloop - for about $750
in 1969 when I was 17. During grade 12 a friend and I rebuilt a lot of it in a rented garage. After graduation (mother gave me a British Seagull outboard as a grad present) we let Vancouver and travelled up the B.C. coast as far as Bella Bella. Took 78 days and loved every minute. Sleeping bags on air mattresses and a coleman stove in the cockpit. The only boat I ever worked on under cover.
I've always loved woodwork - took a lot of shop at school. In 1970 after I got back I worked for a small shop building interior components for Columbia 26 and 34s built under license by Coopers in North Vancouver and then a furniture manufacturer for a while. Decided to make it my hobby as opposed to career after that. 29 years in retail electronics with 10 of those doing installations as well taught me troubleshooting and gave me some background in wiring. Along the way there were the other boats - most didn't require much - a teak swimgrid for my only powerboat in the early 80's, a couple of sailboats I did almost nothing to. In 1987 I purchased a 35' strip planked twin keel sailboat and re-did a lot of the interior - got fancy wiyh ash & teak galley counters, oak and teak salon table and a few other changes. Sold it in 1995. Built a kayak and took a small paddling holiday and after a year bought a 30' fibreglass sailboat It needed rotted wood floors under the sole replaced, galley and salon redone and more. Sold it in 1999.
That brings me to my CS27. It was sailable wen purchased but needed upgrading. I've replaced the fuel tank with a custom stainless one, changed engine panel from aft to forward end of cockpit and from idiot lights to full gauges. DC was so basic with 6 old lights plus running lights and a 32 year old fuse panel (6 fuses) that I removed all and am putting in a Blue Seas breaker panel, Xantrex Link 10, Echocharge, new lights, all new cabling including engine wiring. Rebuilt water pump, rebuilt starter, added strainer for cooling water. Biggest job was a redesign of galley - sold pressure alcohol stove and zipped galley module out. Installed two half bulkheads properly - foam against the hull to eliminate hard spots and properly glassed in to hang new Force 10 propane stove between, sniffer and solenoid with proper propane locker as well. New cabin top clutches to replace old stoppers, new traveler, solid vang, upgraded sheet winches to Anderson 40st and moved the Anderson 28sts to cabintop (I already owned the 40sts so that made sense). Changed head to Lavac. Still to come new headliner, cabin sole, re-do chainplates, all new running rigging, bow roller, dodger, steering vane, lofelines and all new rigging including turnbuckles and toggles, and new through hulls/seacocks and propeller next haulout. And new ports.
The only things I farmed out were fuel tank, starter rebuild, custom stainless clutch bases, stainless bases for Anderson 40sts, and stainless engine panel (never learned how to weld) I will have to get the new bow roller/stem fitting custom made as well. I will do my own rigging , paying for swages at the top and staloks or similar at deck level. The rest I've done myself. I agree with Maine sail that if you do the job yourself the tools are free. I am equipped with all the tools I need for wiring (including the crimpers for 22ga down to 4/0 battery cables, woodwork, mechanical, glasswork, painting etc. If one didn't have good tools that is a big expense but I've collected good tools over many years and I doubt I could replace them for 7k or even more.
What do you gain? If you're good at all these skills, not necessarily fast but good enough to make a professional quality job of it, you should end up with a boat that is better than new, one that you know every inch of. One that you'll take pride in. When something breaks in the future it won't be a disaster and you'll know how to get to it, remove it to fix or replace it.
Financially, it either does or doesn't make sense depending on your intended use and point of view. In my case I will retire in less than 3 years, and this boat is the smallest I can sail and live aboard comfortably (I'm single). I plan to sail south to Mexico and beyond. To buy new would be cost prohibitive. I paid about 14,500 for the boat with 5 sails and a diesel that is older but works well. Paid cash. I've spent about 8,000 (haven't added up all the bills yet) so far and over the next year probably another 7 or 8k to go. Maybe 10k. I couldn't hope to sell for anywhere near that. But it's the least expensive way I know of to get a solid, well equipped offshore capable boat.