Bobs nose cone and low water pickup

[tyst67]

I am interested in purchasing a bobs nose cone but I am concerned with the assembly! My biggest concern is getting the cone on perfectly straight! Who has put a nose cone on and can you send me some pictures and help me out! Is this task extremely hard or is it fairly easy?

[pdt]

there is a little vid on youtube showing a fella fitting one using a lazer to make sure its level before he tack welds it.
this same thing can easily be set up for using just epoxy if that is going to be your method.

the fella puts the lazer from centre of propshaft through the line of the bullet of the gearbox and along the nose cone.

once you get it right from the side its then a simple case of doing the same from either top or bottom.

main thing is to make a simple wooden cradle to hold it still if its off the engine, or on full tilt if still on the boat etc.

do post some pics of putting on and let us know the results performance wise, I am seriously thing about same sort of thing.

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[Fast Fred]

i've done it, a bunch of times. i glue it on then have it tacked, then i don't have to think about if they gots straight. worked at a body shop many moons ago,so it goes easy for me, you need the "feel" to fair it out nice. there is shots on hear of a Nitro lower with a bigfoot cone bein installed on hear, i used all epoxy to fair it out, wet sanded epoxy primer finish.

[pdt]

is it you who has the super nitro gearcases fred ?
if so ive seen your work on those cones, very nice finishes.

[omcstratos]

I used a plum bob and some eyeballin on the nose cone I did. It turned out pretty well.

[pdt]

by using a nosecone are you just wanting it so as to get better water pressure ?
or will it actually give you speed gain ?

the reason I asked is because I fancy this as well, but when reading up on cones lots of people have said it would slow you down unless you
already have a boat that can go over 70mph !!!!!

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[Ron Hill]

A low water nose cone allows you to get water pressure when you raise the motor up. A gearcase with side water pick ups, can be raised about 2-3 inches higher with a low water pick up. Then, you can put a "BIG ***" wheel on your boat and go like "Jack the Bear". I you just put a cone one you will go slower as you have added drag. And if you jut raise the motor without changing the prop, you may also go slower as your small propeller will slip more than it does now.

[pdt]

ok
so lets say the engine is up and you are doing say 45mph with the BIG prop running up high and that's all she can do.

will the cone slow you down at this speed ?
do the cones help with any lift under 70mph or is this realy a myth ? I ask as I don't know.

yes I understand about the low water pick up, I see the cones as being great for this purpose.

but is the cone only good for water pressure ? and below a certain speed would infact hinder speed. ?.

and could this be put on using something like technoweld or similar low heat alloy welding ?



sorry if I am asking too much, but have mainly read from people who try the big sell rather than someone who realy says it like it is.



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[R Pierson]

Ron is 100% correct..All things being the same ( you haven't changed anything set up wise) the cone will slow you down. And...it will add tail lift! Some boats hate that. Example: Hydrostream Valero YT...a 175 Merc with a std lower runs about 70mph. Add the cone and it runs so flat it struggles to get 65. Add a jack plate and different prop and you get back to the 70s but the same thing happened with the stock case. In a exceptional case a cone might be faster if it straightened the angle of attack. ( crab angle too great...we had a laugh about that last time....) Running the gearcase straight has less drag than the cone adds. But the tail lift deal is real. Slower boats ( under 75mph) will find that hard to deal with imo.

[HankFrazier]

Ron is 100% correct..All things being the same ( you haven't changed anything set up wise) the cone will slow you down. And...it will add tail lift! Some boats hate that. Example: Hydrostream Valero YT...a 175 Merc with a std lower runs about 70mph. Add the cone and it runs so flat it struggles to get 65. Add a jack plate and different prop and you get back to the 70s but the same thing happened with the stock case. In a exceptional case a cone might be faster if it straightened the angle of attack. ( crab angle too great...we had a laugh about that last time....) Running the gearcase straight has less drag than the cone adds. But the tail lift deal is real. Slower boats ( under 75mph) will find that hard to deal with imo.
we don't run the factory shape on the bobs we buy we shape them to run like we want them to.

[HankFrazier]

I've never put one on that when i was finished it ran slower than when it had no nose cone even on small motors running in the 40's.

[R Pierson]

Hank,

While what you say is totally true. It doesn't help the guy who doesn't know how to shape the cone. But I'm curious, why would you put a cone on a boat running in the 40's....although some of the gearcases out there are pretty blunt. Take the 3 cylinder/ 4 cylinder loop charged merc's. Those were rather bad. So I rescind the statement as to why would you...

Carry on....

[ima75man]

i build my nose cone out of bondo and then seal it with good primer

[HankFrazier]

Hank,

While what you say is totally true. It doesn't help the guy who doesn't know how to shape the cone. But I'm curious, why would you put a cone on a boat running in the 40's....although some of the gearcases out there are pretty blunt. Take the 3 cylinder/ 4 cylinder loop charged merc's. Those were rather bad. So I rescind the statement as to why would you...

Carry on....

Back in the day we had a 60 mile long river race the boats were 10 ft aluminum with eather 20 hp mercury's or 25hp omc's you couldn't run any set back because of too much transom weight the prop shafts were even with the bottom of boat it was hard to pick up water with out low water pickup although there were some guy's that cut groves on the sides of there gear cases to channel the water to the water intakes the fastest boats ran in the upper 50's the slower boats ran in the mid to upper 40's the prizes were money and boats and motors. this was 35 years ago on the sabine river

[MWhite]

Back in the day we had a 60 mile long river race the boats were 10 ft aluminum with eather 20 hp mercury's or 25hp omc's you couldn't run any set back because of too much transom weight the prop shafts were even with the bottom of boat it was hard to pick up water with out low water pickup although there were some guy's that cut groves on the sides of there gear cases to channel the water to the water intakes the fastest boats ran in the upper 50's the slower boats ran in the mid to upper 40's the prizes were money and boats and motors. this was 35 years ago on the sabine river
yep hank,, back in thoses days we would cut channels in the side of the gear case to channel the water and would sharpen the gearcase as well to cut through the water better,,mine would run around 54 with me a rider and gas. we didn't have nose cones for them little motors like we got now on the 40s. them were some fun days running them river races back then, wish they still had them

[pdt]

The reason I ask is because this.
My boat is /was a pig for speed.
The Boat is Orkney dory 13ft 3 in, very similar to boston whaler classic 13 but built slightly heavier with more of a v in the centre.
Engine is a 3 cylinder 56cu in evinrude 1995.
with a 13x19 my top speed was 38.1 at 5700 rpm, that was with cav plate just 1.5 inches above bottom of boat.
also tried a 13 3/4 x 23 at same height and got 39.8 mph, I know this prop is meant to run pretty high so I have now made a jack plate to
raise it up 7 inches so the propshaft is around 1/2 to 1 inch below bottom of the transom now with a 5 inch setback built into the jackplate.

ive not yet run it like this due to being too busy with other stuff etc, but now im also thinking about water pressure so maybe I might need a low water pick up. ??????

Now putting on a cone with a low water pick up might be the answer as long as I don't slow me down at all, I am not expecting 50 plus mph out of this pig, but want it
as fast as possible with what I have got.
I am hoping that by jacking it up and back the plate will let the prop spin faster dueto half of it being out the water and running high like its meant to.
Hopefully I get 6000 rpm or more like this.
I don't want to cook the motor obviously, but realy cannot afford for anything to rob me of speed, that's why I asked if the cones slow you down in the 40 plus mph bracket.
like said above I would be better off with 70hp carbs, but these are like rocking horse s..t over here, you just cant find them. so for now im stuck with 60hp.

I will probably have to make a cone myself and not sure yet if I am going to use fibreglass or melt down some alloy ( we don't get cones over here, and postage is just too much).
I don't even know yet if by using a set back if it will be too heavy on the transom with the extra leverage, the boat was originaly designed for 50hp and 200 pound motors.
I have taken the boat apart completely and made it a lot heavier on the transom by making it much stronger, and even put down a lot more glass on the hull bottom.

the boat weighs around 250 kilo (500 pound)without engine battery and fuel, so its no lightweight racing boat. so I need all the help I can get with the cone or without it.


ima75man
you say you build the whole cone from car filler ? and it stays on ok yeah ? is that also with low water pick built in or just the cone ?

as anyone built a cone from fibreglass ? and was it any good ?

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[pdt]

Mike
do you have any pics of the channels you put on the gearcase etc ? and did they realy work ok ? sound like another idea if a cone is not going to suit my rig.
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[MWhite]

Mike
do you have any pics of the channels you put on the gearcase etc ? and did they realy work ok ? sound like another idea if a cone is not going to suit my rig.
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yes but I will have to dig around and find them old pictures of the boat and motor I had back then, yes it worked.

[HankFrazier]

Mike
do you have any pics of the channels you put on the gearcase etc ? and did they realy work ok ? sound like another idea if a cone is not going to suit my rig.
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I have built and ran several all fiberglass nose cones on 3cyl Yamaha and tohatsu motors they work pretty well.you will have to touch them up every now and then but you have to do the same thing with the bob's to if you run them a lot.