Lets break these questions down as some people may be able to answer some but not others:
1) Is thier a difference in weight from the 70's 170 from the 80's 170?
steved - do you have literature from both eras?
2) How come my 170 Osprey can hold a 130hp motor while forum members AS 170's of 70's vintage can only hold 85hp?
Here is a link posted by
Jerry-riggedon the coast guard formula for home-built boats. Does the commercial sector use the same calcs - don't know (notice that the calcs don't deal with weight of motor or weight on transom/distribution so I think ther are other things to consider too). Using this formula and arbitrary numbers: if the length of the 170 is 17ft, the beam is 6'10" (mine)(6.83ft) and the transom height is 20" (ours) with remote steering, the max hp is 145. Did they have a motor back than that size that didn't weigh a ton?
If the length of the 170 is 17ft, the beam is 7'10" (newer?)(7.83ft) and the transom height is 20" (ours) with remote steering, the max hp is 180.
You guys can double-check my math. Looks like beam is the key here.
3) Is there a difference in weight?
Dupe of 1 - that was easy.
4) Does the 19-6 in the 70' weigh as much as the 80's 170 Osprey? Any care to elaborate on this?
steved?
5) If so, is better to have the heavier boat with more HP or the lighter boat with less HP?
See number 2 above.
The uscg booklet has a bunch of good stuff in it - mentions Hull ID requirements, ventilation requirements - stuff we've discussed recently here. I don't see a date on this document though to see if its the latest.