Hello everyone - please beware that I am a 'noob' and have only recently got a boat, so sorry if this is a day 1 question...
In a nutshell, I am convinced that the amount of water gushing up the side of my outboard can't be right - I have tried messing around with engine height but am not convinced that is the route of the problem.
A bit of background - the boat is an oversized zapcat style boat (bought from Howy via this forum, thank you forum and thank you Howy!) with a 30hp yamaha 3 cylinder engine. The boat can handle up to 50hp, but I foolishly thought that I wouldn't want anything too wild. Already want a 50hp for it as it is more fun than I thought possible. :-)
I have now been out 4 times, as follows:
-2 on board
-a LOT of water gushing up the side of engine and swamping the back of the boat (it drains out, but there was a lot there)
-being a bit tentative on first trip so didn't realise that the problem went away if you opened it up and went for it.
-once fully on the plane, the boat is superb. Quick but rock steady. Lots of grip from the propellor and lots of fun until you slow down, when niagra falls makes an entrance over the back of the transom
-we tried every trim setting and the problem was there each time. Fastest setting was 3 holes up from vertical.
-2 on board
-I was convinced that the engine needed lifting as the spray goes away once you are on the plane, so I lifted it using an offcut piece of decking plank. I can't remember the exact lift, but it was quite a bit (over 4cm)
-MUCH improved spray situation but the boat felt slower and the propellor was slipping / cavitating (not sure of exact term but the revs would shoot up and all bite was lost)
-GPS gadget was reporting max speed of 28kph until my passenger got out (to be sick! Hangover / wetsuit tight around his neck / sea sickness problem...) and I got it up to 44kph on my own, but felt a bit flighty
-2 on board
-having decided that it was too high, but along the right track, I dropped the heigh a bit to just under 2cm.
-a bit more spray than before and still quite a bit of cavitation
-GPS reported 49kph and it was quite rough
Trip 4 (today):
-1 on board
-decided to leave the height to see if the difference in weight would make a difference
-still quite a bit of spray and cavitation. Topped out at 44kph despite being pretty flat
-I stopped and got rid of the stips of wood that I was using to lift it and immediately noticed a marked increase in grip and speed. It did cavitate a little bit on occasion but not nearly as much and it was faster (56kph). Just felt better allround but the spray was worse again.
I am now torn - the water gushing problem is reduced if you lift the engine but it definitely doesn't help performance.
The propellor is the standard 3 blade job that comes with the engine. Would a different propellor allow you to run the engine a bit higher?
I took the camera out today and there is a dodgy edit at
which I hope helps to show the problem as it is hard to really explain. The video has two heights of engine, but you can hopefully see the issue.
Am I being mad and that is perfectly normal or is there something not quite right? Whilst you can get over it be flooring it and jumping up on the plane, it seems odd that you can't cruise without being drenched?
Any thougts or pearls of wisdom would be very welcome. I am loving the boat and it is a blast, but I just can't help think that there must be a solution to the water gushing up. I have got over my fear of it actually swamping the engine, but would rather it wasn't so bad.
Many thanks for any help,