My name is Matteo. I've just repowered my CD 30C with a Nanni 21Hp (kubota based) and ZF15MIV here in Australia. Unfortunately a few issues came up with Prop sizing, stern gland and rudde during this. Just wondering if anyone has come across this before? Any advice will be much appreciated...
1) Pro: A new Prop was put in with the new engine. I provided Nanni, the engine company, the specs of the boat and they did a propulsion study that revealed to be not very accurate (to be nice). They came up with a 14 x 11, fixed 3 bladed prop that was fitted on the boat. With this, unfortunately, I am lacking 1100 rpm (reaching only 2500 rmp at full throttle, instead of 36000). I contacted a local prop manufacturer and after given them displacement, waterline lenght and engine rpm and gearbox ratio they did another propulsion study for me. It looks like they are suggesting a 13 x 8. I am having the prop removed and trimmed down on Monday next week but before doing so, I thought it might be worth checking if any of you has put a similar size prop once repower with a 20hp engine and how does it go? Please let me know if you have used another size
2) Stern Gland. after repowering, it looks like there no water dripping from the stern gland. Shaft and cutlass bearing seemed to be in good condition so they weren't replaced during the repower. The mechanic who did the install also mentioned that there was no water coming in also when the compressing nut is completely untightened. He also mentioned that the cutlass bearing was very tight but it couldn't see any waterways so he struggles to understand how water could even get in. he noticed that the shaft was a bit worn so he moved it in a way that the gland can now grab on a nice section of the shaft. I am not familiar with the cutlass bearing that was installedbut don't really like the option that my mechanic suggested (drilling another hole and bring water to the glad via a hose) so thought of trying to check if anyone could help shed some ligh on this? I have no clue...
3) Rudder: Sadly enought, the oversize prop cut my rudder when I put the engine in reverse with no tiller arm on (yep, there's a lot of pressure on the rudder in reverse..lesson learnt...). I jumped off and put some putty on the cut. In a couple of weeks, I will be hauling out to do the repair on the rudder and the stern tube (a piece of fiberglass where the shaft exist the boat came off, I assume due to vibration from the shaft when banged on the rudder) and since the rudder makes a bit of noise when I turn it side by side, I am considering of dropping the rudder. It doesnt seems very straigh forward tho and not really sure how to tackle this/time that may take.
Maybe this is something some of you have already tackle before. Any advice on things to check on the rudder to make sure that is fine? Since I'm out of the water I may do too, I believe previous owner have never dropped it so it may be worth checking (if I know what to check for).
Apologies for the long list and once again thanks for your patience and help.
Any advice will be much appreciated.
Look forward to hearing from you
Many thanks
Cheers
Matteo