hull extension in progress with pics

[JaSla74]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Dang Erik. You're like a boat motor Buddha. It all makes sense now

 

[proshadetree]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Turbos have to be selected to what you have.The smaller the turbo the faster the spool up.Large exhaust small impeller = fast boost.Go to big on impeller get turbo lag.There is 2 sides to a turbo drive and pressure.They can be sized to work on everything from a boat to a forklift,Yes they have some turbo forklifts and bobcats.They use them for extra power they also govern at 3000 to 3500 rpm.You can use them even in low engine speeds,off idle.They are not the best for high rpm operation,They die at 4000 to 5000 rpm.Then you have the choke in the system you wont turn 7000 or 8000rpm due to the fact the turbo restricts the intake flow.Most people think turbos are used in high rpm applications only.You can size to what you need.Honda guys are running volvo diesel turbos on d-15s and b 20s they have to rod the crud out of them because the turbo is to big.But 12 to 15 lbs of boost from a standard production turbo is overworking it.Most automotive turbos are only good for about 10 lbs of boost.Compressed air builds heat so now you got to look at an inter cooler.Over 10lbs inter coolers are mandatory.
You can look at wraps to keep temps low under hood.Turbos like wraps keeps heat in and helps to spool the turbo faster.I jumped around a bit but there is more to turbos than just great big and massive boost

 

[jcsercsa]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Man OOOHHH Man ,I am learning so much here, this is too cool!!! John

 

[SuzukiChopper]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

I think we can put erik down for the longest, absolutely most relevant, and most educational post in iBoats history so far.... I studied turbo systems for a couple years and my only reaction is :-O

PS: I'm going to add, although very off topic, erik has to have the coolest avatar too... sorry oops!

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

I'll see what I have in my notes... unfortunately prop design is a very black art as far as the internet is concerned. It's an older field though, so you can find books on the subject here and there... the problem is that they're written for naval architects and aeronautical engineers, so you have to have a heavy math background to keep up. I really don't.

A couple more things that may come up with regards to turbos, I just think I'll throw them out here for thought.

First, I know there are a ton of turbos out there of many sizes, drive types, shapes, etc. with different lag/boost threshold. Even though you can get models that, like a supercharger, provide forced induction across the whole RPM range, they still don't add much, if any, torque.

Show me a turbo that provides an additional 10% torque or more and can still let the engine use 87 octane gas without additives and I'll be interested

Turbo diesels are great... no argument here. They're not gas engines though, so saying a gas turbo is good in a boat because turbo diesels are good is like saying a flats boat gets on plane easily so it'd be perfect for pulling waterskiiers... you're missing the point.

There are other ways than gear reduction prop drives to push a boat, if anyone thought of that. If you use something other than a gear drive, you can transform a turbo engine's RPM into useable power. But, all of the mechanisms I know about are less efficient at using engine power than a prop. So for a given engine size, even with a turbo, you get less thrust than just using the same engine with a direct gear drive and a prop. Three examples of non geartrain drives that come to mind are:

* Waterjet drives
* Hydraulic drives
* Hybrid gas/electric drives like electric azipods


Erik

PS: Re: Avatar... thanks. I like that comic, and Belkar appeals to me. I can't wait for the next panel monday... looks like he's going to open a can of whoop a**...

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

... by the way, if oops wants to use exotic fuels, I know where he can get a design for a generator that produces 27 volts at 430 amps in a 15 inch cylinder 40 inches long that weighs 255 lbs.

One of those would probably run a medium size water jet, a very high torque electric motor (which has a completely flat torque curve) or a nice azipod drive. As a bonus they produce hot water and surplus electricity full time

On the downside they require tons of insulation on the fuel tanks...

Erik

 

[proshadetree]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Not meaning to offend but I'm a show me guy.Iv read on this board that nos has no place on a boat I did it and it flew 20mph on topside.But I did blow my junk up.I just didn't want to rule out turbos. It, like I stated earlier, will bring its own state of challenges.I like the big blocks for torque and reliability.Aluminum will bring weight down and add to performance to.Lots of options when it comes to power plants.And the last is what you want to make work.I wouldn't have a supercharger or a turbo on a boat,I'm getting old.But let that wild hair step up and ill probably blow up another one.

 

[Renny_D]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

I'm right in the middle of movin my office but it was good to see the topic stilll going. I'll try to respond tomorrow or latest monday.. in the mean time

http://www.youtube.com/watch?v=WdrZGjKf7-A&feature=related

http://www.youtube.com/watch?v=yz1Ozirbl_g&feature=related

and my favorite though not a v8 but a rotary..

http://www.youtube.com/watch?v=vi_zm0OAJwY&feature=related

 

[Renny_D]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

This one might interest all of you - it's a twin turbos and a bbc. The best part is it's all tucked away neatly below unlike the previous. Somehow I think the turbos are working on this boat...

http://www.youtube.com/watch?v=3U9nYk3kcdg&feature=related

The turbos are working in this one too !!

http://www.youtube.com/watch?v=3KgxNFutVJI&NR=1

Ok back to work..

Renny

 

[jcsftwre]

Re: hull extension in progress with picks page #3 post #55

Re: hull extension in progress with picks page #3 post #55

the idea is to get the floor totally smooth....no bumps or space for air to gather around.....once again ....as this is a hulll....no air can get into the glass....or it all has to be ground down

While reading the Iboats ?hull extension in progress with picks? manifesto my attention directed to page #3 post #55 I read repeatedly that ?there should be no air bubbles in the fiberglass while laying it in the hull.?

Is this because if there were to be a bubble left behind that it would then be a flex point and weakening the boat? Thus endangering the two beautiful water skiing bunnies being pulled behind, all the while skimming over the water at 45 miles an hour?

That really is a serious question with a little joke at the end. I want to make sure why you stated it more than once.
I am grinding my boat down for my rebuild (it?s about a 1969 boat) and I found no less than three in the shell that must have been there from the factory. Right now I am debating after I fix the three holes and one crack that I have found I wonder if I should lay a piece of fiberglass across the whole floor and build it up one layer for strength. In smaller pieces at a time I would assume.

Do you repeat that statement because it is for strength and safety or is more from being a perfectionist and for looks?

P.S. great idea having the outline at the beginning! I'm sure all of us will end up reading through it one time all together (as I did) but I will be hitting the points that match what I'm doing on my boat as I go.

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Not meaning to offend but I'm a show me guy.Iv read on this board that nos has no place on a boat I did it and it flew 20mph on topside.But I did blow my junk up.I just didn't want to rule out turbos. It, like I stated earlier, will bring its own state of challenges.I like the big blocks for torque and reliability.Aluminum will bring weight down and add to performance to.Lots of options when it comes to power plants.And the last is what you want to make work.I wouldn't have a supercharger or a turbo on a boat,I'm getting old.But let that wild hair step up and ill probably blow up another one.

Well, if you put NOS in a boat, you'll increase operating temperature, operating pressure, and torque, not to mention RPM. It's like using a high octane fuel plus additives.

So if you're below your hull max speed and max prop RPM, yes you'll get a boost, and you'll feel it in the seat of the pants

But, it's sort of impractical effort wise because you are using a small NOS tank...if you use a big one, or in other words use NOS for any extended period, you burn your engine.

I think people say NOS has no place in a boat because it won't provide continual HP gains... the power it provides is short term, which isn't too useful for offshore racers... better to spend the weight and money elsewhere. It's not so good for pleasure boaters either, for some of the same reasons.

But it'll work in a boat if you're under your max prop RPM, sure... you'll fly like a bat out of hell


Erik

 

[erikgreen]

Re: hull extension in progress with picks page #3 post #55

Re: hull extension in progress with picks page #3 post #55

While reading the Iboats ?hull extension in progress with picks? manifesto my attention directed to page #3 post #55 I read repeatedly that ?there should be no air bubbles in the fiberglass while laying it in the hull.?

Do you repeat that statement because it is for strength and safety or is more from being a perfectionist and for looks?

Oops will have to answer that, but here's my 2 cents worth.

You're sort of right with the "flex point" idea... bubbles form a difference in structure of the finished fiberglass, where stress is not distributed evenly across the material. In a molded solid glass hull that means there's a spot where there's no glass, so the surrounding material will have to handle transmission of the force that would have gone through the bubble.. so there's additional stress there which leads to failures. It also provides pockets for condensation to collect... long term this can freeze, blister the surface of the glass, etc.

In a cored hull bubbles mean the skin, which provides most of the strength, is not adhered to the core material, which although it can be minimally strong, must be there and must adhere to the skin in order to have the needed strength. This case is more dangerous than a molded hull because typically a bubble means a spot where the panel is less than half the strength it would have if it were fully glassed in that spot. So that would lead more often to failure, sometimes in spectacular fashion.

Neither of these is a huge problem in non structural locations, like hatch covers, consoles, etc. In a deck it's probably ok provided you don't have more than eg. 25% bubbles. The deck is structural, but it's under less stress than your hull.

It all depends on how anal you want to be. If I'm laying glass I typically remove through grinding any piece of glass cloth that has formed more than 5-6 bubbles larger than my little fingernail when it's hard. In some cases you can use a syringe to fill the bubble with resin, but I usually just grind it out and redo.

Edit: To clarify, I don't grind out the whole piece unless it's really small.. usually I do the bubbles plus a 6 inch radius, then re-glass after acetoning.

One more thing... bubbles are more serious in poly resin fiberglass than epoxy, because epoxy won't delaminate as easily as poly, and epoxy usually has excess strength for any boat design due to its physical properties... epoxy compensates for poor quality construction in many cases.

Erik

 

[oops!]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

renny....thanks for the vids....keep the stuff comin bud !


btw....im going to go look at another shop tommorow

 

[oops!]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

I read repeatedly that ?there should be no air bubbles in the fiberglass while laying it in the hull.?

Do you repeat that statement because it is for strength and safety or is more from being a perfectionist and for looks?

You're sort of right with the "flex point" idea... bubbles form a difference in structure of the finished fiberglass, where stress is not distributed evenly across the material. In a molded solid glass hull that means there's a spot where there's no glass, so the surrounding material will have to handle transmission of the force that would have gone through the bubble.. so there's additional stress there which leads to failures. It also provides pockets for condensation to collect... long term this can freeze, blister the surface of the glass, etc.

It all depends on how anal you want to be. If I'm laying glass I typically remove through grinding any piece of glass cloth that has formed more than 5-6 bubbles larger than my little fingernail when it's hard. In some cases you can use a syringe to fill the bubble with resin, but I usually just grind it out and redo.

Erik

yep.................. erkis got it.....in the hull....no air bubbles are allowed....there are baisically two types of air in a laminate.....first of all....the larger type....that erik describes.....(the size of a small fingernail).....these are not allowed because of the reasons he states....ie weak spots in the hull....condensenation....cracking...ect...ect.

the second type is a lot more harder to spot and a lot worse than the larger type bubbles.
they are called micro bubbles.....uasually caused by a poor wet out process, or incorrect substraight/resin temps.
micro bubbles are a gazillion little bubbles about the size of a pin head.....they are through out the glassing job. wide spread over an entire area.

these type of bubbles are quite a bit more tricky, they cause a weak laminate. every where there is a bubble....there is no adheasion or "bond" to the substraight.....this type of bubble causes a really weak section of glass....constant flexing on it can crack it, as the resin rich layer between the layers of glass is brittle.

in the extension of the hull....because of the flex areas of the new section....and because the joint of extension was right ahead of the motor and the forward joint near the contact point of the new plaining surface, stregnth of the laminate was paramount,so i was really anal about working out all the air.

in a perfect world......with a standard glass job there will be no air.....however in regular....non structural repair......air happens !

I am grinding my boat down for my rebuild (it?s about a 1969 boat) and I found no less than three in the shell that must have been there from the factory. Right now I am debating after I fix the three holes and one crack that I have found I wonder if I should lay a piece of fiberglass across the whole floor and build it up one layer for strength. In smaller pieces at a time I would assume.

couple of things here......you can just fill the hole in your hull with peanut butter....depending on how big the air bubble was in the origonal construction....you might want to add milled fibers or 1/4 inch chopped strand bits.

the boats in 69 were uasually pretty strong hulls, so unless you felt the hull was weak and it was flexing.....or you grind away too much of the hull in prep for the strings or even rough and scuffing,
you wont need the extra stregnth.

but its your boat.!!!!! you can do what you want to it....if you want to feel more secure knowing there is a extra layer of glass in the hull ....go for it..... (a layer of 1.5 oz csm over the hull wont add very much weight....about 15 lbs).....because of all the grinding....and the extension....i used a full wrap of 1708....from the tip of the bow.....all the way up the new transom.

hope that helps

cheers
oops

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

This one might interest all of you - it's a twin turbos and a bbc. The best part is it's all tucked away neatly below unlike the previous. Somehow I think the turbos are working on this boat...

http://www.youtube.com/watch?v=3U9nYk3kcdg&feature=related

The turbos are working in this one too !!

http://www.youtube.com/watch?v=3KgxNFutVJI&NR=1

Ok back to work..

Renny

They're operating, sure.. but with what prop and drive unit? What are the turbos adding over and above what those engines could produce without them?

I'm pretty sure with that first hull, assuming it's light enough, an EFI 9.4 liter chevy engine like they use (gen 6 or so) could come close to those numbers with the right prop, without the turbo.

With the same prop that's giving the first boat the 114mph pass, what's the hole shot like? And if you know, what's the prop slip at 114?

You CAN put turbos on a boat engine and have them spin, just like you can attach NOS injectors, or a special magnet that "aligns" the fuel molecules, or a set of pasties with tassels. The question is, whether it improves performance, and for how long. A half pound of C4 detonated off your transom will give AMAZING performance... for a quarter second or so.

I think a lot of the companies and private users out there who add these turbos to boats either don't know much about boat drives or don't care. Notice how all the videos they post are short "speed runs" where they list the max MPH? It's almost like guys who are drag strip wizards with hot rod engines decided to buy a boat one summer and see how fast it'd do the quarter mile

I've yet to see any boat engine with an added turbo that performs better than the same boat without the turbo, or more to the point performs better than just spending the money on a larger engine in the first place. I eagerly hope someone can come up with solid dyno torque numbers (measured at the prop) along with a prop that can use the torque, to prove me wrong.

Come to think of it though, I may be making assumptions... Oops hasn't really said whether his planned use of the boat is quarter mile runs at high speed past the ladies followed by a leisurely putt around the lake for the rest of the afternoon to use the rest of his gas. If that's the case, maybe we DO need to put in an NOS system and turbo

Erik

 

[oops!]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

I want to put up pics, part numbers and naration of Marinizing a SBC and a SBF. Just need a few more round tuits.

i want to do a boat biulding materials list for the site but i need some "round tuits as well.........

do you know if round tuits are avalible on e-bay?....or perhaps the site that sells the muffler bearings and the flux capisitor......i just keep running short of the durn things...! lol




id love to go to a county fair like that one bubba !

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Math I don't mind (I am a mechanical engineeer) but you are right in that there is very little information out there, even in book form. I suppose it comes down to not telling your competition about your secrect sauce. A 5% improvement in efficency would be a huge advantage over the other guys.

True... I doubt most of them get even that... mostly they seem to be looking for ways to make a high speed prop give a better hole shot, or make a hole shot prop give an even better hole shot. Of course some of them are working on making high speed props that go faster too.

The navy's done a lot of work making props quieter, of course.

Tweaked props are mostly for rec boats, IE planing hulls. Except for the new azipods that are being deployed here and there, most of the oceangoing ships use old design props or very similar ones to the props that went on ships 50 years ago. Canal boats and tugs that need lots of low speed thrust off a small engine or max thrust off a big engine use a clipped prop with a kort shroud.

Even rec boats with the fancy props like offshore racers with Arneson drives don't use one huge engine with an expensive prop. They get more push using multiple engines. Barring an unexpected design breakthrough, you just can't design a prop to give EG. 40% better performance at all speeds than what already exists.

I think the cutting edge of research now is props for azipods... since they're mostly electric, you have constant torque at any RPM, so you can design a prop to take advantage of that.

I dunno, maybe someone someday will build a useful, durable variable pitch prop for small boats. There have been a couple designs, but they weren't very long lasting...



Erik

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

On a boat, the ducted fan is called a "Kort Shroud"... it's a well-known way to get a ton of thrust at the low end of your rpm range... as you found out it's limited at the high end... check out a google search for Kort shroud, you'll learn a ton.

A transmission in a boat like you describe might or might not be useful... it depends on a lot of factors. More torque is generally better, but unless you can simultaneously vary your prop diameter or blade count, you can't really take advantage of it.

A variable pitch prop would be needed additionally... go low pitch when starting out to use that geared down torque on hole shot, then higher pitch to reach full hull speed with lower torque once you're on plane. Gear for increased RPMs to match the prop pitch as you go up. To match the two you'd need computer sensing and control though, or else an extra arm or two or maybe a copilot.

But the limit would be when the prop reaches max pitch, when you're basically pushing water in a circle rather than pushing it backward.. when the blades are almost parallel to the keel. At that point all the RPM and torque in the world do you no good... you need another prop pushing, or a bigger prop for more thrust, or a water jet.

I suspect that you could reach the same speed without all the fancy parts by just using a larger engine and a larger prop with a standard drive... in the end you'll be limited by your hull, and the need to have a prop in the water at all.

A hydrofoil would be simpler and faster

Erik

 

[erikgreen]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

Absolutely! And do keep us informed of your progress (but don't share too much... if you solve that particular problem, I guarantee you'll be able to retire on the proceeds of the patent. There are a LOT of kort shrouds in use

Erik

 

[proshadetree]

Re: hull extension in progress with picks

Re: hull extension in progress with picks

The boat I sprayed was a berkly jet on a 18ft sidewinder 455 olds.I ran a guy with a big block chevy 2 fours and a ported berkly.150 shot all summer long.Swapped to a 250 and she went lean and blowed a hole in the piston.In tennessee where I run 6 to 10 seconds at 80plus and you run out of lake quick.60 on flat water with a good wax on the hull was all she got before.
80 was way to fast for that hull,In my opinion.I was younger and couldnt die like all young men think.30 to 40 is flying now.But at the time it was the only way I could get near him.You never felt it ,you knew you were going faster, it just happened.The old olds was runnin 4500 to 5000rpm on the bottel it turned somewhere around 7000.I was lucky to have only melted a piston.way to many rpm for a bone stock olds.