Isn't it the truth? After four decades in the boat business and six years of major upgrades on my boat, I am convinced that the best rule of thumb for budgeting something like an engine re-power is that the component is 50% of the cost. You'll probably do a bit better than that when the project is done but you had better have access to at least that much money to be sure you can complete the project.
BTW that Beta is not a 20 hp engine in the same way that my 2QM20H is. My current engine produces an honest 20 hp at 2600 RPM.
That Beta is only producing 20 hp at nearly 1000 RPM more and way past the peak of its torque curve. I would really miss the wonderful sound of my heavy, high torque diesel. My 2QM20H is right about at the peak of its torque curve at 2600.
The Beta is producing about 14 hp at the peak of its torque curve and 2600 RPM. I would need to buy a new prop as well, even if I could live with the loss of 6 hp.
I would want the next size Beta which increases the cost. Getting these modern, fast turning, diesels to run at the optimum 80% hp in cruise is hard since they are set up to produce these high horsepowers and high RPM for marketing reasons. The reduction gears to get the prop speeds down into a usable range are not easily available in small sizes except by special order in which case they can cost as much as the engine. I also need a down angle gear which drives the cost even higher.
I'm burning joss sticks to the engine gods that my Yanmar appears to be still running in its prime.
