My input (bearing in mind i operate a Hovtec OTTER)) is that reducing vibration (Simple Harmonic Motion) is essential to ensure ideal power transmission, with subsequent decrease in operating noise, (ie you reduce hull vibrations -AKA- noise)
To THIS end, ive incorporated an antivibration damper in the V belt drive up to the OTTER thrust with very considerable effect, reducing vibration and any feeling of "harshness" through out the rev range.
On my previous Hovercraft that I designed, (KINGFISHER 1) I have taken phone video of belts operating at their harmonic state which show that the pulleys can exhibit 50% reduction in engagement, ie 50% of the driving/driven V surface was not touching! On that craft I positioned damper blocks at 35 % and 60 % distances from the ends, ie driven and driving sides were PREVENTED from harmonic vibration and the improvement was considerable.
On YOUR craft- IS there noticeable increase or higher vibration at your cruise revs? IMHO only by videoing the belts at those revs 3000rpm? will your vibration video be instructive, not as much at 1200rpm IMHO. Can you fasten a video camera and power up on shingle 3 inch pebbles (to absorb all lift) and check to see if there is measurable vibration / power transmission loss?.
As Ive said before (I think) Perhaps remove the lift area cover to check IF that is strangling the lift input area. It will only take 5 mins to check this out, and let us know. As Ive also said before, I did exactly this 30 years ago on a craft to encompass the noisy lift, only to find that the lift actually produced was strangled, although noise was reduced a bit. Upon removal of said cover - the lift was SO improved, that REVS could be reduced again! In short, my noise reducing cover reduced LIFT rather than noise!!!! History sometimes helps and this piece of hovercraft history is passed onto you FOC!
