Hey mate 👋 Cheers 🍻 It will make a slight difference, I would. Make sure to sharpen it not just on the edge but blend it in over at least 30mm. Can’t wait to see your vid on that, the chainsaw motor looks like it has some good power. All the best Aussie Boat G 😎
Ok so we share the same love for fast outboards and ways to improve efficiency at minimal costs, i have a C115TLR on a 15' flats boat and am considering a transom mounted pickup so i can run motor where it should be was wondering if you had a template or som good measurements for the inlet hole in side of case? I know you guys down under love the 3cyl stuff but wished ya did more with the older looo charged V4's anyway great videos keep em coming
Hi mate, I don’t have any measurements for the 115 but I would take the lower unit off then the impeller housing and impeller base plate so I could look down the water tube. Once I could look down the water tube I would plan a spot to weld in a inlet wash side. you will probably have to blank off the original strainers and use a good transom scupper. cheers 🍻 Aussie Boat Guy 😎
Hey mate, I actually had a broken case that I cut a section off the front, then welded a heap on the front and shaped it. I should have taken a cast off it though. Cheers 🍻
Nice video, real nice workmanship. Is there a chance to see the "scupper" ,how it mounts to the hull and do you use some type of filter before it gets to the motor?
Hi mate, yep, it does make quick appearances in some vids already but not in detail or anything. the scupper is actually the original strainer from the 5hp that I modified on a bracket to bolt to the transom. I will try do a video on it mate. cheers 🍻 Aussie Boat Guy 😎
Hi mate, Yeah, there is so many little things can be done. I haven’t got a video on drilling the housing. I think it makes a slight difference but it does make the motor very noisy so you need to weigh that up. I’ve had mates drill them then put cover plates back over the holes because it was too loud and annoying. Cheers 🍻 Aussie Boat Guy 😎
The trailing edge fairing could be a moot point as once surface running the water line should be at prop shaft level, looks proper though. The next trick is to extend the prop shaft allowing fairing of the prop through exhaust so more water is fed to the blade disc area. Then redirect exhaust outlet to above water line.
Hi mate, Yep definitely true, I just did that training edge fairing as a test just for myself (did a run at full depth in comparison to the standard case, 1.7 kp/h different with all the mods including the trailing edge) Obviously you only do those mods if you want to raise the case up but I was wondering what difference they make at full depth, not much. Now it’s surface piecing, I would not fair the trailing edge of the prop because I would be making a little displacement hull. The gearcase is now like a mini boat hull and more than 1/2 the prop is out of the water, the trailing edge of the torpedo needs to be square. Ps: you are the first to pick up on that upper trailing edge is not much point when surface piercing, well done 👌. Like the way you think mate. Cheers 🍻 Aussie Boat Guy 😎
@@25hpboatracerman Avon Descent and Dinghy Derby in the (very) distant past, I'm impressed with the shear WTF lets do this and see what can be extracted from a 5hp frame. It would be interesting to run the numbers on prop RPM v pitch v water speed to gauge blade slippage and efficiency. Re. fairing the gearcase "I would be making a little displacement hull." Hadn't thought of that, I'm not very knowledgeable on displacement hull drag rise, other than I know the formula. Is displacement boat hull speed a factor of increasing speed increases low pressure around hull sucking hull deeper into the water thereby increase displacement and wet area?? Or something else. Is this relevant to a gearcase that is finely faired?? The slippage numbers would tell a story whether more effective (wet) blade is warranted. The things that come out of blokes sheds, great post and project.
I'd say yes to the displacement theory sorta like a hook or rocker in hull, faster the speed the more the suction to water especially on the slick water days, hook and rocker are next level of man's mindset very few out there understand or even heard of the issue and it occurs on every boat on its trailer for long periods of time.
Yes, I have never really gelled with the chine area side rollers instead of good quality spine rollers taking the weight and nylon skids just kissing the hull along the chine area. for the reasons of hook. At least for the smaller boats. To the gear case, would it matter if there were an increased low pressure area along the lower portion of the gear case when running on the surface? It is not like we are trying to create lift as in a planning hull, just minimise drag. Drag in the case of the gearcase is skin drag and form drag and induced drag (induced drag being the drag associated with displacing the water to create lift. Of these, form drag and skin drag would be the dominant. To reduce skin drag we need to energise the boundary layer on bodies that are not large (ie. low reynolds numbers such as a grearcase) by roughening the surface. And for form drag essentially minimise the disturbance to the water, bring it back together if we can and minimize the eddy created by its passage, at least until doing so requires extra wet area which sends skin drag to the forefront. But if a little extra skin drag reduces form drag and brings the water back to more of the wet blade it maybe that we get less slippage on that blade and hence less induced drag. If you can follow that you've done well. @@mariebrooks1822
Hi mate, Well, the 5hp started off only reaching about 29 kp/h stock but now reaching over 45 kp/h It’s not just the gearcase mods, it’s all the mods combined that got the better speed. You would only modify the gearcase like that if you were going to raise the motor and surface pierce the propeller. Check out my vids on surface piercing propeller and testing a jack plate it shows sone of the other things I did plus you can see the gearcase in action. Cheers 🍻 Aussie Boat Guy 😎
if in Sarawak, sir, we will drill the bottom part for the water to enter and we will change the hose that goes to the impeller and go down....if you want to see how you can
Hi mate, I made the nose cone, can’t buy anything that small and the right shape. I might be producing them in a few months. Cheers 🍻 Aussie Boat Guy 😎
Hi mate, Yeah I know that method but I cannot run my exhaust out the top because I will get in trouble with the authorities. I need to keep my exhaust running out the propeller unfortunately. I am now looking for a 85hp Yamaha carburetor, do you do much to adapt it? Thanks, Aussie Boat Guy 😎
Hi mate, I made it myself. I probably should have taken a mould of it and got some cast. You can make them just out of bondo or two part body filler, it works fine and sone that many times. Cheers 🍻 Aussie Boat Guy 😎
We had actual speedmaster gearboxes for our racing boats, no neutral or reverse, pull the string and gone. They had water pickups on the bottom of the torpedo.
😂😂 Well the scupper the hose is connected too is actually the original strainer from the outboard, just mounted on the transom, it basically sits on top of the water while the boat is running, really no drag. If you watch the other videos related to the 5hp you will see the point which is to raise the motor and surface pierce the propeller. The 5hp motor is now reaching 45.1kph so the mods are working. Over 15kph gain with all the mods combined on that motor with more to come. Anyway, same modifications I use on other larger motors I raced completely which work well. All the best
Spraying the gear case bright silver definitely improves performance! 😉
Hi Champ,
That is the main thing, must be silver or the other mods don’t work 😂😂😂
good job mate looks so good the racing gearcase.Good work mate its been a great series on the 5hp motor.
Cheers mate,
Had a blast modifying the little 5hp, I am still hoping to get it up to 30 mp/h
So about 3kph to find still.
All the best
Aussie Boat G 😎
That is cool looks like a good shape . I’m making the Skeg for my longtail at the moment looks like I need to sharpen the trailing edge a bit 👍
Hey mate 👋
Cheers 🍻
It will make a slight difference, I would.
Make sure to sharpen it not just on the edge but blend it in over at least 30mm.
Can’t wait to see your vid on that, the chainsaw motor looks like it has some good power.
All the best
Aussie Boat G 😎
Awesome, and beautiful craftmanship. cheers mate
Thanks mate,
Having fun with this one ☝️
Cheers 🍻
Aussie Boat Guy 😎
ive just found your channel, every video is awesome great work.
Thanks mate,
Welcome 👍
I really appreciate your encouragement.
Cheers 🍻
Aussie Boat Guy 😎
Another great video mate, thanks for the great project. Cheers
Thanks mate 👍
Cheers 🍻
Ok so we share the same love for fast outboards and ways to improve efficiency at minimal costs, i have a C115TLR on a 15' flats boat and am considering a transom mounted pickup so i can run motor where it should be was wondering if you had a template or som good measurements for the inlet hole in side of case? I know you guys down under love the 3cyl stuff but wished ya did more with the older looo charged V4's anyway great videos keep em coming
Hi mate,
I don’t have any measurements for the 115 but I would take the lower unit off then the impeller housing and impeller base plate so I could look down the water tube. Once I could look down the water tube I would plan a spot to weld in a inlet wash side.
you will probably have to blank off the original strainers and use a good transom scupper.
cheers 🍻
Aussie Boat Guy 😎
Very nice work 👍
Hi Mate,
Thank you! Cheers!
Aussie Boat Guy 👌
👍🍻the question we all wanted to know
Cheers 🍻
which propeller did you use? nice job!
Hi Champion,
I have used the modified standard aluminum propeller plus a little bronze race propeller which was better.
Cheers 🍻
Aussie Boat Guy 😎
Did you 3d print the mould for the gearcase nosecone for casting.?
Hey mate,
I actually had a broken case that I cut a section off the front, then welded a heap on the front and shaped it.
I should have taken a cast off it though.
Cheers 🍻
good vid, the mods look great
Cheers mate 👍
All the best
Aussie BG 😎
That's a sweet mod👍
You would make a fortune selling this to the Tinny Rats on the Gold Coast! 😉
😂😂😂
yeah I have some experience with those guys.
I’m sure I would be a tinny rat if I was younger 😁
Nice video, real nice workmanship.
Is there a chance to see the "scupper" ,how it mounts to the hull and do you use some type of filter before it gets to the motor?
Hi mate,
yep, it does make quick appearances in some vids already but not in detail or anything.
the scupper is actually the original strainer from the 5hp that I modified on a bracket to bolt to the transom. I will try do a video on it mate.
cheers 🍻
Aussie Boat Guy 😎
So many little things you can do for improvement ,well done ,do you have a video on drilling the housing for exhaust improvement or is it not worth it
Hi mate,
Yeah, there is so many little things can be done.
I haven’t got a video on drilling the housing.
I think it makes a slight difference but it does make the motor very noisy so you need to weigh that up.
I’ve had mates drill them then put cover plates back over the holes because it was too loud and annoying.
Cheers 🍻
Aussie Boat Guy 😎
Nice video thanks for showing us. Where did you get the aluminium nose cone from?
Hi mate,
Cheers 🍻
I made that tiny nose cone,
Was thinking I may cast some in the future.
All the best,
Aussie Boat G 😎
@@25hpboatracermanyou made that nose cone yourself????? Wow. Sitting here wondering how that could be done. You sure do excellent work my man
Привет друг, выхлоп на тохатсу 5 осуществляется через винт или через дейдвуд? Сними обзор на гоночный винт на тохатсу 5
Привет помошник,
выхлоп через винт
Wheres the build video out for tthis motor im curious.
Hi Champion,
The video is named Modifying An Outboard on my channel.
All the best,
Aussie Boat Guy 😎
The trailing edge fairing could be a moot point as once surface running the water line should be at prop shaft level, looks proper though. The next trick is to extend the prop shaft allowing fairing of the prop through exhaust so more water is fed to the blade disc area. Then redirect exhaust outlet to above water line.
Hi mate,
Yep definitely true, I just did that training edge fairing as a test just for myself (did a run at full depth in comparison to the standard case, 1.7 kp/h different with all the mods including the trailing edge)
Obviously you only do those mods if you want to raise the case up but I was wondering what difference they make at full depth, not much.
Now it’s surface piecing, I would not fair the trailing edge of the prop because I would be making a little displacement hull. The gearcase is now like a mini boat hull and more than 1/2 the prop is out of the water, the trailing edge of the torpedo needs to be square.
Ps: you are the first to pick up on that upper trailing edge is not much point when surface piercing, well done 👌.
Like the way you think mate.
Cheers 🍻
Aussie Boat Guy 😎
@@25hpboatracerman Avon Descent and Dinghy Derby in the (very) distant past, I'm impressed with the shear WTF lets do this and see what can be extracted from a 5hp frame. It would be interesting to run the numbers on prop RPM v pitch v water speed to gauge blade slippage and efficiency. Re. fairing the gearcase "I would be making a little displacement hull." Hadn't thought of that, I'm not very knowledgeable on displacement hull drag rise, other than I know the formula. Is displacement boat hull speed a factor of increasing speed increases low pressure around hull sucking hull deeper into the water thereby increase displacement and wet area?? Or something else. Is this relevant to a gearcase that is finely faired?? The slippage numbers would tell a story whether more effective (wet) blade is warranted. The things that come out of blokes sheds, great post and project.
I'd say yes to the displacement theory sorta like a hook or rocker in hull, faster the speed the more the suction to water especially on the slick water days, hook and rocker are next level of man's mindset very few out there understand or even heard of the issue and it occurs on every boat on its trailer for long periods of time.
Yes, I have never really gelled with the chine area side rollers instead of good quality spine rollers taking the weight and nylon skids just kissing the hull along the chine area. for the reasons of hook. At least for the smaller boats.
To the gear case, would it matter if there were an increased low pressure area along the lower portion of the gear case when running on the surface? It is not like we are trying to create lift as in a planning hull, just minimise drag. Drag in the case of the gearcase is skin drag and form drag and induced drag (induced drag being the drag associated with displacing the water to create lift. Of these, form drag and skin drag would be the dominant. To reduce skin drag we need to energise the boundary layer on bodies that are not large (ie. low reynolds numbers such as a grearcase) by roughening the surface. And for form drag essentially minimise the disturbance to the water, bring it back together if we can and minimize the eddy created by its passage, at least until doing so requires extra wet area which sends skin drag to the forefront. But if a little extra skin drag reduces form drag and brings the water back to more of the wet blade it maybe that we get less slippage on that blade and hence less induced drag. If you can follow that you've done well. @@mariebrooks1822
Any numbers on what improvement you got for this cool looking mod?
Hi mate,
Well, the 5hp started off only reaching about 29 kp/h stock but now reaching over 45 kp/h
It’s not just the gearcase mods, it’s all the mods combined that got the better speed.
You would only modify the gearcase like that if you were going to raise the motor and surface pierce the propeller.
Check out my vids on surface piercing propeller and testing a jack plate it shows sone of the other things I did plus you can see the gearcase in action.
Cheers 🍻
Aussie Boat Guy 😎
if in Sarawak, sir, we will drill the bottom part for the water to enter and we will change the hose that goes to the impeller and go down....if you want to see how you can
If for racing not suitable like this😅
@@felixsueljepiugun3109
Hi 👋
Yeah, I saw how you do it, very cleaver 👍
I’m not racing, just for fun.
Cheers 🍻
Aussie Boat Guy 😎
did u buy the nosecone? If yes were? looks cool😁😇
Hi mate,
I made the nose cone, can’t buy anything that small and the right shape. I might be producing them in a few months.
Cheers 🍻
Aussie Boat Guy 😎
cool i would buy 100%😁@@25hpboatracerman
👍👍👍👍👍👍👍
Thanks mate.
All the best
Aussie Boat Guy 😎
There are another method for water inlet that we used on racing in Borneo 😮.. it no need hose just do some modifications on gearcase
Hi mate,
Yeah I know that method but I cannot run my exhaust out the top because I will get in trouble with the authorities.
I need to keep my exhaust running out the propeller unfortunately.
I am now looking for a 85hp Yamaha carburetor, do you do much to adapt it?
Thanks,
Aussie Boat Guy 😎
Can you show the thing on the back of the boat for the water please
Sure, I will do a quick vid over the weekend.
Cheers 🍻
Aussie boat Guy 😎
where did u get the nose cone from?
Hi mate,
I made it myself. I probably should have taken a mould of it and got some cast.
You can make them just out of bondo or two part body filler, it works fine and sone that many times.
Cheers 🍻
Aussie Boat Guy 😎
We had actual speedmaster gearboxes for our racing boats, no neutral or reverse, pull the string and gone. They had water pickups on the bottom of the torpedo.
Yeah ran a speedmaster too on a 44xs trunk with a modified 3 cylinder Yamaha power head.
Loved that motor.
Cheers 🍻
Aussie Boat Guy 😎
Do you sell the nose cones?
Hi mate,
I will be in the future, not quite yet though.
cheers 🍻
Aussie Boat Guy 😎
@@25hpboatracerman cheers brother. You do incredible work. Warm regards from the southern Caribbean.
All that to reduce drag on a 5 hp just to add the drag back in with the water hose??????????
😂😂
Well the scupper the hose is connected too is actually the original strainer from the outboard, just mounted on the transom, it basically sits on top of the water while the boat is running, really no drag.
If you watch the other videos related to the 5hp you will see the point which is to raise the motor and surface pierce the propeller.
The 5hp motor is now reaching 45.1kph so the mods are working. Over 15kph gain with all the mods combined on that motor with more to come.
Anyway, same modifications I use on other larger motors I raced completely which work well.
All the best