roaster tail problem (pics)

[Darren b]

Hey guys I have a 14' starcraft with a 50hp evinrude. At half to full throdle I got water splashing into the transom and 2 side roaster tails..the engine has power trim but does not help at and trim location. Any thoughts? Thanks

 

[GA_Boater]

Is this a long shaft motor on a short transom or vice versa? How about a photo of the stern/motor relationship with the boat on the trailer.

 

[Darren b]

No Title

Here you go...

 

[Frank Acampora]

Try raising the engine a inch or two. From the photo it appears that the anti-ventilation plate is below the hull bottom . The splash plate above the A/V plate appears to be even with the bottom

 

[Texasmark]

Take a tape measure and measure from the top of the transom where the engine mounts to the bottom of the boat. Then measure from the same point on the transom to the anti vent plate on the engine. The anti vent plate is that horizontal plate just above the prop. Going to bet as Frank and GA eluded that you are running a 20" engine (and it is as I can tell by looking) on a 15" transom which may measure 16 or 17" and referred to as a 15.

In short we are all telling you that your engine is too low. On that boat with the keel cap which causes turbulence right in front of the engine and can cause ventilation if the engine is too high, your best height would be for the anti vent plate to be even with or about 1" below a straight line extension of the bottom of the boat as it crosses the engine as it is sitting (vertical) in the picture. Just take a yardstick, place it on edge, about a foot and a half all in contact with the bottom of the boat. Where the yardstick crosses the engine is your measurement point.

 

[Darren b]

Let's say I have to raise the engine 2 - 3" can i just simply mount a piece of square stock aluminum between the engine and transom and remount engine? Thanks

 

[Frank Acampora]

Just use something to space it. The 'rude has multiple mounting holes in the transom brackets so it is likely that you may not even need to drill new ones in the transom. Once bolted back in place there is no need for a spacer.

 

[Darren b]

Cool thanks..

 

[GA_Boater]

Just use something to space it. The 'rude has multiple mounting holes in the transom brackets so it is likely that you may not even need to drill new ones in the transom. Once bolted back in place there is no need for a spacer.

Exactly. I dropped mine using the slotted mounting holes and had almost the same over transom splash. Raise it as far as it would go and the splash disappeared. The boat picked up top speed with the raised motor, too. No spacers needed, either.

 

[Darren b]

Great to hear.. I will try this weekend.. thanks

 

[gm280]

Some folks actually install a "Jack plate" for that very reason. However, if you can raise yours without buying such a plate, then you can pocket that money and use it for fishing gear... :smile: :thumb:

 

[Sea Rider]

Had same exact issue, now combo is running like a champ.

Try this :

Raise engine fully up using holes and go for a wot spin, back splash should disappear, lower engine a hole at a time till water flow skims right under small upper water deflector plate, that's the sweet engine/transom height for any engine. Probably when lifting engines existing drilled engine holes won't match a exact skimming under upper deflector plate, dial a hole to achieve the closest to that setting (red line) forget all about AV plate height, was not invited to the lower leg water party..



Actual water splash is produced when water flow at speed hits right above small water defector plate, somewhere between both horizontal yellow lines. Flow needs to be cut at sharp front angle and pass slightly under deflector plate as in this example. To dial sweet height must pull head out transom to check at which lower leg is flow passing by, if you find this issue to be extreme have a boater follow you at close distance side of rear leg and check. Could take some time to dial, but it's all worth going for and boat happily after...





If it were a clamp model it would be a much friendly model to dial exact sweet height by means of wooden shims, once dialed can proceed to bolt down engine on transom. The height must be dialed while engine sits at 90 deg angle to transom when on plane. AV plate must ride parallel to water level.

Happy Boating

 

[Darren b]

Thanks Sea Rider. For the great info I will be doing the work this weekend... I will post my results Monday. .. thanks too all. Great forum

 

[Sea Rider]

You are welcome.

Forgot to add that boat must have weight evenly distributed throughout deck to achieve a correct ballanced boat while running near even with water level at plane.

Happy Boating

 

[Darren b]

My Dad and I lifted the engine as high as we could,and still mount on the transom safely. The anti vent plate is 3/4" below the bottom of the boat. Took it for a rip and 85% less spray. I am really happy with it thanks to you guy's. But a seam to have another little problem. When the boat is at WOT and I trim the engine up it starts to bounce pretty good so I had to either ease up on the throttle or trim down the engine. Also the boat is a 14' aluminum starcraft rated for a 45hp and I am running a newer 50 hp evinrude.. the boat seams to be really light. I was thinking of tossing some sandbags under bow just for safety. Thanks

 

[Sea Rider]

The new AV plate height it's just a plain number reference. So you are at the highest engine sitting level, that's with all 4 bolts screwed on transom, right ? Can you post a new pic showing the new engine sitting position to have a look. Do you have power trim or manual trim ?

How's hole shot, assume you are running factory delivered porp, right ? how about max achieved rpm at full throttle, do you have an installed tach to check that out ? You are in the right track to dial opt engine height, latter will work with wot rpm and trim to optimize combo performance.

Seems that water flow is still hitting slightly right over water deflector plate when at plane, you had a huge shower going on at back engine compared to now.

Happy Boating

 

[Darren b]

I will get some pics this weekend.. boat is at camp. Thanks