Opinions On Nose Cones
 

Well I'm not going to be able to do and extentionb box this year so I was thinking about putting a nosecone on (Bravo 1) and maybe cutting the cavitation plate down (making it narrower) to try to get a few more MPH.
Right now I'm running 80 , and that is trimmed out almost all the way. It seems that in this position the cavitation plate would be dragging thru the water.
As far as nose cones what benifits do they offer and what brands are recommended?

from what i've heard above 80 is wher eyou start seeign teh benfit of them. You can reduce your prop slip at these speeds. I believe around 8- the stock bravo lower starts to reach it hydrodynamic limitations and starts to not cut teh water so well anymore. The nose cone might help. I have also heard at high speed they improve eth over handling due to the increased hydrodymics.

ttt

Hey 26scarab,
I would be careful messing with that cavitation plate. Way back when I was running an outboard with a Merc chopper prop. It would cavitate like a bi__h when I would take off. I added a plate similiar to a whale tail and it would controll the amount of slip that the prop would have. With out the plate 6k out of the hole, with the plate it would hook at 4k.. Worked good in my situation. I have no idea what it might do in yours.. but just passin on my experience..


Oh yeah the nose cone will add speed if you need to over trim to hold the bow up. The hole that is dug in the water at 80mph with the blunt object you now have limits water to the blades of the prop. The newer lower unit designs are better than the old ones. They say that around the 80mph range it will make a difference. I have had the best luck with Hydromotive, but only because my Checkmate hull liked it..

Good luck..

Dick

Got one cheap make me an offer!!!
 

Have heard from folks who have LOST mph with the addition of a cone. On a boat that makes best speed with moderate trim, no cone may be best. If you are trimming way positive, then the "hole" theory makes sense. More leverage (stern jack or extension box) may be your best answer.

I've put cones on outboards before. Here's my advice.

If you know somebody with a cone, try to "borrow" their drive (assuming you have stock power) and try it (same gear ratio will be necessary for apples/apples test).

If no borrowing available, tack weld the cone on in three spots, use bondo for filler and go test. That way, if it sucks, you can peel the bondo off and cut the welds, remove the cone. A quick sand job on the welds and some primer and paint and you are back where you started. If the booger really does work, do the above, and remove it, strip the paint and rouch up the case and bond it properly to your drive.

My 2cents

I used Leading Edge nose cones from Teague Custon marine
and picked up 5-6 mph on my 33 Scarab avs.

Hey Chuck
I put on a Hydromotive nosecone. I don't really know if it helped speed or not because I made other changes at the same time. It went on well and looks good. Figure about 3 nights work.

Nose cones work very well. The biggest problem with people losing speed is improper alignment during installation. Alignment is critical. Leading edge is a great nose cone, wpm is a good one also. If you don't want to install them yourself Leading Edge wil install them. They do a great job.

I just added two Hydromotives to my "old style" Bravos. The drives sit very low on my boat (Cafe Racer) so I've heard they should help my speed. I'll know in a few weeks..

I read an articale, It could have been Teague in PB, that if you are running a conservative X dimen, read low, that the nosecone will give larger gains than if your drive is set up high and therefore the "gains only over 80mph" does not nessesarily ring true........Ill dig for the quote.

For you guys installing nose cones on the older drives with the front oil drain plug. What I did about the drain hole was to drill a hole larger than the drain plug centered over the drain plug. I then carfully tapped the hole in the nose cone for a 1/2 inch NPT brass plug. Be carefull because you have to thread it shallow since you don't want the plug to penetrate deeper than the inside surface of the nose cone. This procedure is done just before you mount the cone to the drive. Once the nose cone is mounted to the drive clean out any excess epoxie from the drain hole and any that gets into the threads. When the epoxie has set then thread in the BRASS plug untill snug - don't overtighten. Then cut off the part that sticks out beyond the side of the nose cone (leave a little so that you can file-sand it smooth to follow the same curve of the nose cone. Then drill two 1/8 inch holes about 1/8 inch deep into the face of the plug spaced as far apart as you can without getting too close to the threads. You can now use these holes to remove the plug to get at the drain plug underneath and there wont be the water flow disruption from the original big hole. I used two allen wrenches and a screw driver to twist out the plug but the y do make a tool for this type of plug - hole set up.

Nose cones or not
 

Hi!

I have a Phantom 25 w/Promax 300. I have experimented with nose cone and stock lower units. My set up is an outboard, but hopefully you can draw some ideas.

Set up is: Gears 1.75, CMC powerlift with 5,5 inches of setback, 26 inch labbed Tempest prop, propheight approx. 2.5 inches below bottom, positive trim, hull weight approx. 2.300-2.400 lbs.

My experience with a nose cone - Bobs Nose Cone factory installed with a high performance torque tamer - was not as advertised. Top speed with a stock lower unit was 76 mph on glassy water and no wind. With a nose cone, slip was reduced, but top speed was the same. The rpm dropped 100-150 rms. Midrange speed increased somewhat, approx. 1-1,5 mph. The boat runs 51 mph at 4.000 rpms. With nose cone approx. 52,5 mph.

To outweight the longer bullet of a nose coned lower unit, you have to in my experience either run in excess of 80 mph or run the propshaft higher to get less drag. In my case I could not rise the lower unit higher before rpms rincreased causing excessive slip. Water pressure with my TM lower unit was sufficent at all times.

So if you running more than 80 mph you should gain speed. If you also run a high x dimension / combination of the two, you should also gain speed. Please be aware of that if you use extendion boxes, your lower unit will be lower in the water (the water will hit the lower unit higher as more setback you have), but it will be easier to lift the bow with less trim = more speed. Best solution = shorter lower unit + extension boxes.....

Testing will only tell.

Cheers, Toffen G - Norway

Toffen,
I just read an article explaing what you said
I found it surfing , I think it was from R & R propshop.
I know the box and shorter lower are the way to go but no $$ for that at the moment.
If I can at least go the same speed at a lower RPM that would be worth the nose cone. Of course a couple of MPH would be better !:D

decisions
 

External steering is a must before adding a nose cone.
Hydromotive is my choice if your boat needs positive trim to run good.