You are my Hero! I starting to understand and this was excellent. 40 years without a refresh as a EE = knows nothing...ty so much. BTW: Excellent attitude...we make each other greater: no other way.
So I spent many years working with 11" Hamilton's in work boat applications. Like all Jets, they are RPM sensitive. We were spinning them at 2,850 per engine MFG's requirements (CAT 3208T @ 240hp). But one day after the engine was out of warranty, we upped the fast idle and spun the motor to 3,200 - what a difference. Of course it was over-boosted and would not live long at that setting. Now that I'm retired, I'm helping my neighbor rebuild a 1970's era roundy-round jet race boat. Has an early Berkeley 12 JB pump, but was tweaked for racing with an SS A Cut impeller. We're assembling a mildly stout 454 BBC that ought to make 400+ HP. The pump will tell us once it's all together ... Jets are big fun 🙃
I'd be interested to see what an actual dyno shows compared to the Berkeley pump curve at your max RPV. I dissected the curves long ago and discovered they are EXACTLY cubics, which means they are probably just theory, and won't align exactly with reality. I also found several different sets of "official" curves for the same impellers. It would be nice to get some dyno numbers to resolve these lingering difficulties.
How about making the end of the nozzle variable as in an airplane afterburner? Load up when you take off and trim smaller as you speed up. They solved the thrust problem in an airplane. What’s so difficult to do it in a jet pump in a boat?
Good point. There is very little development in the jet boat world. The Berkeley pump is maybe 45 years old, the Hamilton 212 maybe 30 years old. General design and structure of boats is static. Those "in the know" generally have strong opinions about "the best way to do things" and that is how they are already doing things. Jet boat manufacturers can be very successful simply by assembling the pieces and making something that is similar to an existing boat. This strategy would not work in the airplane world, which relatively speaking has more innovation baked into the cake.
granting engine power is enough, is it safe or fair to say, a 12" impeller can be paired with a 6" nozzle? please teach me. thank you. have a nice day.
You are my Hero! I starting to understand and this was excellent. 40 years without a refresh as a EE = knows nothing...ty so much. BTW: Excellent attitude...we make each other greater: no other way.
So I spent many years working with 11" Hamilton's in work boat applications. Like all Jets, they are RPM sensitive. We were spinning them at 2,850 per engine MFG's requirements (CAT 3208T @ 240hp). But one day after the engine was out of warranty, we upped the fast idle and spun the motor to 3,200 - what a difference. Of course it was over-boosted and would not live long at that setting.
Now that I'm retired, I'm helping my neighbor rebuild a 1970's era roundy-round jet race boat. Has an early Berkeley 12 JB pump, but was tweaked for racing with an SS A Cut impeller. We're assembling a mildly stout 454 BBC that ought to make 400+ HP. The pump will tell us once it's all together ...
Jets are big fun 🙃
I'd be interested to see what an actual dyno shows compared to the Berkeley pump curve at your max RPV. I dissected the curves long ago and discovered they are EXACTLY cubics, which means they are probably just theory, and won't align exactly with reality. I also found several different sets of "official" curves for the same impellers. It would be nice to get some dyno numbers to resolve these lingering difficulties.
That sounds like a great setup!
To easy if U give a example.. thank u 🙏
How about making the end of the nozzle variable as in an airplane afterburner? Load up when you take off and trim smaller as you speed up. They solved the thrust problem in an airplane. What’s so difficult to do it in a jet pump in a boat?
Good point. There is very little development in the jet boat world. The Berkeley pump is maybe 45 years old, the Hamilton 212 maybe 30 years old. General design and structure of boats is static. Those "in the know" generally have strong opinions about "the best way to do things" and that is how they are already doing things. Jet boat manufacturers can be very successful simply by assembling the pieces and making something that is similar to an existing boat. This strategy would not work in the airplane world, which relatively speaking has more innovation baked into the cake.
granting engine power is enough, is it safe or fair to say, a 12" impeller can be paired with a 6" nozzle? please teach me. thank you. have a nice day.
Just read a teory, sorry .. 😀
So how do you measure the measurement for
Brilliant
When's recess? Lol