ABC Sib-Rib Installation Guidelines.-

[Sea Rider]

Re: ABC Sib-Rib Installation Guidelines.-

Weimed, both are 20" shaft engines, first is mounted on a 18" transom, the second on a 16" transom. Usually forum boaters recommend to sell the long and buy a short shaft engine, that could be costly. By adding a false water deflector plates can use long shafts on short to medium height transoms and forget all about unwanted out or over transom water splashes. 2 down issues, bear in mind that you'll be draging a longer tail if boating near shallow beaches and you'll need to make your own WDP as they are not commercially available....

Happy Boating

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

1: will the 20" shaft lower your performance because it is deeper in the water (mph)?
2: can you please tell me the benefits of this fin thing under my prop?

 

[Sea Rider]

Re: ABC Sib-Rib Installation Guidelines.-

Weimed,

1-Drag is slight minimum if water splash is diverted onto wake, if not water crawling through rear tail will drag you the most. Have a short and long shaft 18 horses. The 20 only loses 20 rpm compared to the short at wot, both opt height transom seated.

2-Lower add-on devices are for engines running on shallow rivers which has tree branches and other unwanted submerged objects like rocks, animals, etc Protects lower tail and prop from hitting hard objects. Is it supposed to be a different device for any other particular aplication ?

Happy Boating

 

[fbpooler]

Re: ABC Sib-Rib Installation Guidelines.-

Weimed, putting a 20" motor on a 15" shaft will definitely add lower unit drag. Not only does the foot lower the point of thrust in relation to the bottom of the hull but the area of the extra length of wetted lower unit creates drag. The ideal thrust location would be straight in line with the transom, but this is of course not realistic.

The next time you are in the water, run your hand edge first through the water and feel the drag caused by your hand. Then increase the speed of your hand and feel the difference.

The splash off the lower unit has no effect on the drag of the motor.

Before the advent of through hub exhaust, some pretty fancy designs of lower units were sold in an attempt to cut lower unit drag. Racing motors had very short lower units with small, high pitch props to minimize drag. The motors were noticeably slower than later designs with thru hub exhaust motors of the same horsepower because of drag with exhaust snouts creating further drag. Lower unit drag can be a real problem which increases as speed increases.

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

it fin looks like it protects the skeg. I like it because when i carry my ob to the car i can rest it on that fin without damaging the skeg on the concrete floor. My concern is performance. Will i get more drag because of it? based on the design i think i will get very minimal drag. Just not sure to keep it on or off

 

[fbpooler]

Re: ABC Sib-Rib Installation Guidelines.-

It adds drag, so it is up to you whether you use it or not. I would remove it myself, as the waters I frequent do not need the device.

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

Do you carry your ob? Or is it mounted 100% of the time on the boat?

 

[mrdrh99]

Re: ABC Sib-Rib Installation Guidelines.-

I agree with weimed..... as someone who also carries motor every trip it seems helpful to have extra protection for prop etc...

 

[fbpooler]

Re: ABC Sib-Rib Installation Guidelines.-

I have carried various size outboards up to 18 HP since the early 60's and am yet to damage the skeg of a motor. It is up to him whether or not he sees a need for the device. If he lays the outboard on its side while transporting it, he should be certain all water is drained before putting it on its side. An open exhaust port would be a bad place for salt water to enter.

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

This 4 stroke is weird I Drove with it on its side and all the oil leaked All over my trunk. I find it weird. After i got home I replaced the oil and I have not seen a drop spill. I am under the impression I have to keep it as upward as possible

 

[fbpooler]

Re: ABC Sib-Rib Installation Guidelines.-

A four stroke can be laid on one side only, otherwise the oil leaks out. I think the steering arm is the side to lay it on but could be wrong. Do not lay it on the wrong side. The skeg attachment may not allow it to be laid properly on its side, be careful.

If you do not have the owners manual, it may be available on the web. I know Tohatsu/Nisson has theirs on their websites.

Remember, the oil in a four stroke is located in a pan, not a sealed chamber. What brand is your motor?

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

MERCURY - ( 15 H.P. (2006 ))
Serial No: 1B281025 Model No: 1F15203FD

theres an arrow pointing the way it needs to be layed down. I might have put it down the wrong way

 

[Sea Rider]

Re: ABC Sib-Rib Installation Guidelines.-

Weimed,

So it's a long shaft with skeg protector mounted on a your Zodiac's short height transom ? If so, extra 5" leg will drag you down if experiencing severe water splashes out transom. BTW that skeg protector is mostly used while riding stone rivers to protect lower tail from direct hits, you must unlock engine while cruising so engine pivots upwards when hitting something. Useless if boating on sand, mud beaches.

If you don't have severe water splashes out transom, the drag of that skeg protector should be minimum if fin rides paralell to water level once on plane, nothing to worry about. The only way to know excatly your LU performance lose due to drag is going for a wot spin with an induction tach and a GPS and check max rpm and MPH achieved, then remove protector and check agin. Idealy both test must be done in flat, no wind water conditions to compare both runs.

Happy Boating

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

Sounds good. My OB is 15" shaft.

 

[Sea Rider]

Re: ABC Sib-Rib Installation Guidelines.-

Sounds good. My OB is 15" shaft.

You're just inquiring about the pro and cons of havinga a skeg protector, right ? Or you do have a short shaft with that skeg protector installed ? As stated before, useless for standard boating.

Happy Boating

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

ok screw it i will take it off. i figured it had some kind of propulsion to make my ob faster but if there is no benefit unless used in shallow waters screw it.

 

[Sea Rider]

Re: ABC Sib-Rib Installation Guidelines.-

ok screw it i will take it off. i figured it had some kind of propulsion to make my ob faster but if there is no benefit unless used in shallow waters screw it.

Weimed, once protector is off will need to fill those screw holes with epoxy, resin, silicone or will have corrosion there if left unattended.

Happy Boating

 

[Guest]

Re: ABC Sib-Rib Installation Guidelines.-

Can you link me to a good one? I was looking at w-e-s-t m.ar.ine the one they have most people use on wood

 

[fbpooler]

Re: ABC Sib-Rib Installation Guidelines.-

Something like J-B Weld, liquid metal, or the kneadable epoxy sticks would fill the holes, but do know that when they set up, they are about as hard as soft steel. Make sure they are flush before they completely harden. I repaired a hole in an aluminum canoe with the liquid aluminum and it is as good as new after many years of use. I also fabricated a lip seal mount on the lower end of a crankcase which previously was only sealed with the lower bushing.

All propulsion from your motor is delivered by the propeller. Anything bolted to the lower unit which rides below the surface only takes away from the power generated with drag. Don't believe the Dole Fin adds and such advertising claims. You cannot bolt something to the lower unit and increase the power from the prop.