Re Outboard set up

Hi i have a stacer Proline 385 with a Johnson outboard 30hp 1999model the man i brought it off had it on his quintrex for many years. he just upgraded. i put motor on went out to the lake to try it but it dosent get any where real fast. i have noticed the CAV plate sits about 4 inches above bottom of transom would that be the problem. does the cav plate have to be exactly level with bottom of transom. the transom measures 20 to 21"
any help would be appreciated

 

G'day farmer, it sounds like you have a short shaft motor fitted to a long shaft transom height. Yes, the cav plate will need to be no higher than the bottom, or it will be unable to stop air being sucked into the prop and over-revving. Just how you go about correcting this situation, is the problem. Ideally, you'd get a long shaft engine to replace it.

 

Thank you very much for your help, when i brought the motor i asked the man 3 times on the phone will motor fit a 20" transom he said yes it will, it's the first time i have taken it out i come back home measured the motor comes up nearly 16" and the transom 20 to 21"
Regards Farmer

 

Cutting the transom down is a possible option, but it would de-value the boat, imo, and cost money, a jacking plate is a possibility as well, but will cost and not ideal either. No easy way to solve it that won't involve spending money.

 

I might ring man back and tell him the motor is a short shaft not a long shaft like it says in his description he had advertised on on Gumtree, or only way is sell motor .

 

Worth a try, if it is 16" it is definitely a short shaft, and he should do the right thing as the goods do not match the description given.

 

I asked him 3 times he said yes will fit a 20" transom so i took his word for it , will give it a go
Thank you for you help

 

need a photo of that

 

how would i put a photo on here to show how outboard is sitting

 

Welcome to the forum farmer680. To post photos, click Go Advanced or the blue Post Reply button, then click Manage Attachments and select the photo to upload and click upload. Then submit the post with the photo(s) attached.

 

Thank you very much

 

Here are pictures of outboard hope this helps the cav plate sits 4" above bottom of boat i measured the leg from top of transom mount to bottom cav plate and it's between 15 and 16 " the transom is between 20 and 21 "

 

another photo of outboard set up

 

From the pictures it doesn't look like the cavitation plate is that far above the bottom of the boat. Are you measuring to the actual cavitation plate not to the rib above where the bolts that hold the lower unit on are. What was it doing when you tried it on the boat, you said the boat wouldn't go. Was the motor revving up like it was in neutral this is what will happen if the prop is cavitating or was it just not producing enough power.

 

From his pictures, it is a short shaft engine. The contrast to a 30 hp long shaft is evident (compare distance from the lower engine mount to the lower unit) from the pics here:
http://www.smalloutboards.com/e3086l.htm