Something wrong here...I think

[Surffx]

Following the rules of the “Read this first!!!” sticky:

1. Top speed/rpm not right
2. Aluminum 17m
3. 14.5 diameter 17 pitch
4. WOT 4900 rpm 33mph loaded (6 people, 30gals fuel)
5. 2018 Yamaha F150
6. 2018 Robalo R207 Length 20’ 7” dry weight 3200 lbs according to website specs

I just bought a new 2018 dual console Robalo R207 and am just past 10 hours of break in. Top speed is 33mph which seems pretty low to me. I do live at 4500’ elevation so I understand that will make a difference. But I can’t get my rpms higher than 4900 which doesn’t seem right either. I did a lot of reading on the posts here and engine height seems to be something that comes up a lot. This boat was literally put together less than six weeks ago at the factory. Could they have put the engine in the wrong position? Or do I have the wrong prop? Or a combo of both. I would like to get a SS prop that can give me all around good performance and the correct operating RPM for the engine maximizing it’s horse power. I would really rather not have to mess with the engine height if possible. The dealer is 2 hours away. Right now looking at the engine there are four holes, it is currently on the second one from the top. Any help would be appreciated. Thanks!!

 

[porscheguy]

Engine height should be set so that the cavitation plate is even with or slightly above the keel of the hull. You can increase the height about 1” for every 12” of setback from the transom. In English, your motor height is probably correct. Engine height changes should be something a dealer should be willing to do at least once at no charge after the customer takes delivery, but that depends on your dealer.

Your boat should have a 2:1 ratio. And WOT engine speed should be 5000-6000RPM. Prop testing should be done running light. But I think it’s safe to say that if you want to go stainless, get a 15P. Probably a Yamaha Reliance SDS. Yamaha props are manufactured by Turbo. I see several companies selling powertech which appears to make knock offs of other brands. They’ve got a model called the Rel3 which claims to be equivalent to a reliance. I know some very knowledgeable people who stand behind powertech props.

 

[jimmbo]

If the engine was mounted by the factory, it is probably at the correct height, in regards to the prop they would chose. Did the dealer reprop the unit? At speeds below 50 mph mounting it higher than the bottom of the hull doesn't do much. Your performance, considering the altitude and the load, is not bad for a 150. You will have to drop a few inches in pitch. I wonder if Yamaha offers a High Altitude gear set?

 

[WesNewell]

Both my new boat and my bothers were factory mounted and both were mounted too low. I called the factory and the tech their agreed and they set up with the dealer to have it raised, Made a big difference in performance. The 17p prop you have sounds right, but you should be getting close to 40 mph with everything setup properly. The best way to check your engine height is to look at the av plate while at wot. If it's below the water line at top speed, it's mounted too low and acting like a speeed brake putting more strain on the engine which keeps the rom's down. With the hull on your boat, I'd guess it should be at least 1"inch above the bottom of the boat when the av plate is in line with the hull. If it is mounted too low, I'd suggest an adjustable jackplate. Less than $200 on ebay, then you can easily change height yourself according the load. With a jackplate, the engine needs to be mounted even higher.

 

[Sea Rider]

Dealers just sits engines on transoms and voilá, you must take their word for granted that engine sits at the sweet transom height spot as are the so called experts riggers. This engine transom perfect match heigh is a fine tune thing done on water test only and not on a dry installation.

Check if there's a high elevation jet kit if being carbed or whatever if being an engine with injectors. Both fuel systems needs to work with less pitch props to pull wot revs up at least to middle rpm range as loadd along using the least fuel octane rating for engine to work much better, not same as when at sea level though as there's less oxigen for engine to breath properly, burn correct air/fuel mixture to work efficiently

Happy Boating

 

[Faztbullet]

Here in the USA 90% of dealers don't rig boats anymore as they come pre-rigged from the factory. These are setup from factory on water testing results.