Hi guys is any body running a yamaha f 200 i4 on a 208 at the highest (last hole on the outboard mounting bracket)? Raising the anti ventilation plate and inch or two above the bottom of the hull (transom). Believe I could go up one more to be able to see the anti ventilation plate at speed and get a a little higher rams at WOT. Getting 5600 now. Thanks trapper
anti ventilation plate height
- Thread starter trapper
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'Rule of thumb' is vent very slightly above the water surface at speed, but getting splashed. Sometimes you can go a hole or two higher, depending on boat, and you'll know when you're too high ... :wink:
You might be able to go a little higher, but keep in mind gurus will advise to keep the AV plate in line with the bottom of a conventional transom. As mentioned, once you are too high, you will know it.
I don't think there is a simple answer. So much depends on how the boat is used and loaded. In addition, the adjustments to height affect some ares of performance more than others.
One thing is sure, at some point performance will suffer as the prop rides higher. For example, if the blades are in air at the top of the rotation, you may cause more cavitation and loose thrust. At the same time, straight line speed can be improved by have the cav plate ride high. With higher mounting and depending on cavitation and other prop induced disturbances, you need to sure that you don't starve the cooling water intakes On motors with temp guages, you will see the temps rise but on motors with alarms only, you won't know until the overheat sensor is triggered.( Assuming that you hear it
So before you try to figure out the optimal setting, you need to identify your goals, Time to plane, top end speed, performance under heavy load, handling in rough seas, etc. The prop selection has a lot to do with the net results also and one height may work better with a different prop than another.
I always recommend that you start with the settings recommended in the Yamaha rigging guide. Since the I4 weighs about the same as the older SX, those settings should be a good starting point
One thing is sure, at some point performance will suffer as the prop rides higher. For example, if the blades are in air at the top of the rotation, you may cause more cavitation and loose thrust. At the same time, straight line speed can be improved by have the cav plate ride high. With higher mounting and depending on cavitation and other prop induced disturbances, you need to sure that you don't starve the cooling water intakes On motors with temp guages, you will see the temps rise but on motors with alarms only, you won't know until the overheat sensor is triggered.( Assuming that you hear it
So before you try to figure out the optimal setting, you need to identify your goals, Time to plane, top end speed, performance under heavy load, handling in rough seas, etc. The prop selection has a lot to do with the net results also and one height may work better with a different prop than another.
I always recommend that you start with the settings recommended in the Yamaha rigging guide. Since the I4 weighs about the same as the older SX, those settings should be a good starting point
Thank you all for your insight into my question.Yes I started with the Yamaha rigging guide and since have raised it one hole with good results. I realize that I could raise it one more hole and see if it works well. In my corner of the world it is expensive to move it once never mind twice if it is a no go. I guess the other question is, I am running, depending on the load, with my motor trimmed up to near the top of the trim tilt gauge. Could I possible raise the outboard one more hole and run a little lower on the engine trim? Just trying to get my WOT up a little higher like I mentioned earlier. Wanted to re pitch my Yam Reliance ss SDS 17p to 16p but have been told my two prop shops that the Yamaha ss blade are very brittle and changing pitch would probably crack the prop and if weldable could lead to stress fractures around the hub.A new one is now $740 plus tax CAD (Yes the slippery loony, our CAD dollar) So will try and sell it if raising the outboard does not work. Anyway exploring ways to get a couple more hundred rpm's on the F200. Thanks again guys for your expertise, great to belong to a group who is so willing to share. Cheers, trapper
ausway, Any issues with your outboard at the highest hole? Do you have a hard top and or a kicker. My ventilation plate is approx. 1/12 inches above the the bottom of the transom. What pitch blade are you running and what make? Maybe if your not busying you can't sleep, you would not mind letting me know. I may have beat this subject to death, my apologies! Cheers, trappe
On my 208 I had stainless Yamaha 15-1/2 X19 on F200 yamaha and was awesome for cruising but dragged the A** for long time , WOT was 5100 so I replaced it with Solas stainless 14-3/4 X17 at 4000 rpm. doing 42km/h it using 1.6 km per 1 litter and WOT is 5800 rpm and doing 71 km/h sorry about metrics but that is how is gauges are set up .
I'm very happy with Solas performance as I do lot of costal bars crosing and offshore fishing .
no hard top , no overheating , no slipping , and vent plate is just under the water still .
I'm very happy with Solas performance as I do lot of costal bars crosing and offshore fishing .
no hard top , no overheating , no slipping , and vent plate is just under the water still .
Thanks ausway, One more question on this subject and I will try and shut up. How high is your ant vent plate from the bottom of the transom. Difficult to tell from the pics (3 or 4 inches?) I have a similar weight with the F200i4 plus over a 100 lb. kicker Thanks for any responce, Cheers trapper :bang
Thanks ausway, Thinking about purchasing a lifting ring and renting a hoist and raising it myself. Want to change the transom cap from aluminium that is pitting badly to a stainless one. The tough part, I think is removing all the old caulking before applying the new. Cheers, trapper p.s. If anyone has some tips they would like to share on raising their outboard with an engine hoist, I would appreciate any input. Thanks
An engine hoist may not raise high enough depending on whether the boat is on a trailer or blocked. There should be a lifting ring on the power head. Take a look. A block and tackle or chain hoist will work if you have something strong to hang it from.trapper said:
ausway hello, One more question regarding your engine height. What bar on the trim can you cruise at? Do you get any prop blow out (prop ventilation) when cruising then increasing rpm to WOT. What was you final distance from the keel to the anti ventilation plate, and is that the last hole on the bottom of the mounting bracket? with thanks, trapper