Yamaha Shaft Extension Kit for F350,,, is it ok ?

[rasemuae]

Hi,

I installed a twin yamaha 350, with 25 inch shaft instead of the recommended 30 inch. shaft since no counter rotation are available in 30 inch over here in Dubai (Emirates);

In order to fix them, I positioned the engines a bit distant from the recommended position, as per the wellcraft scarab manufacturer;

Boat performance is fine, its almost same as per the manufacturer performance data sheet; Issue is the planing time ! its taking me over 25 seconds to plane against the 4-5 sec reported by wellcraft; top speed is less by 10% as well as cruising speed;

Question is, do you recommend me to buy and install the Yamaha shaft extention from 25 to 30? Any issue with that?? Easy? Problems? different than originally 30 inch engine??

Thanks

[boscoe99]

A photo or two of the lower units/mid-section while the boat is running with the engines trimmed to their normal position would be very helpful.

Is the anti-ventilation plate well out of the water or???

What do the motors sound like when you advance the throttle when trying to get onto plane? It may be that the incorrect length of the motors with respect to the transom is causing the transom to inhibit the flow of water to the propellers.

Yamaha does not offer an extension kit by the way. Bay Manufacturing offers Yamaha extension kits, but unfortunately, not for the F350.

[rasemuae]

Hi I can manage the planning putting tabs down etc,,,, but, accelerating while you have people in a channel is really annoying since you can't see much . . . attached are some pix :-)

A photo or two of the lower units/mid-section while the boat is running with the engines trimmed to their normal position would be very helpful.

Is the anti-ventilation plate well out of the water or???

What do the motors sound like when you advance the throttle when trying to get onto plane? It may be that the incorrect length of the motors with respect to the transom is causing the transom to inhibit the flow of water to the propellers.

Yamaha does not offer an extension kit by the way. Bay Manufacturing offers Yamaha extension kits, but unfortunately, not for the F350.

[99yam40]

A photo or two of the lower units/mid-section while the boat is running with the engines trimmed to their normal position would be very helpful.

Is the anti-ventilation plate well out of the water or???

.

He was asking for pics of the lower part of motor directly behind the transom looking down at the anti-ventilation plate.

Sorry, but those pics will not give a view of what he was looking for.

maybe pics of a straight edge coming off of bottom of boat by motors to show how high the anti-ventilation plate is in relation to the boat bottom while on trailer would be easier, but his request would be good also to see if the anti-ventilation plate is well out of the water or not.

You do put the tabs down when getting on plan every time do you not, it should bring the bow down but will cause some resistance.
I think I have read about smart tabs that automatically drop down themselves to help with planing so you do not have to do it manually

Maybe you have too much weight in the back of the boat.

if the only thing that is different is the length of lower unit and position of motors and not prop or weight in boat then that has to be the problem