Let the eldest son, the second son and the third son contribute a, b and c respectively, then 3a=b+c+8, 5b=a+c+8 and 2c=a+b+8. If you subtract two or three formulas, you can get c=2b. Substitute c=2b into the second formula to get a=3b-8, and finally substitute both a and c into the first formula.

Then C = 32/3 and A = 8. So the final result is 16/3+32/3+8+8=32. So the value of the boat is 320,000 yuan.