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I like the idea for some information to be out there and in one place to send folks with questions. If the answer is not here anyone can call me or email me, or get hold of me. I hold nothing back when it comes to boat set up. Now if you ask for prop numbers... well that might be pushing it.
Here are some basics assuming you understand the basic terminology.
For the larger hydros, kneeling and not laying down. I am thinking 750CCMH (44CI) and 850CCMH (3 Holer or SEH).
A decent starting point for an average adult on a somewhat recent hull that has not gained weight, and is of the designer’s original plan.
Set the engine up with a 1/8" Tucked under measurement. Also start out with he center of the prop shaft roughly 1/2" below the bottom of the ACTUAL bottom of the boat. Do NOT measure this from inside the tunnel of the boat. Your measurement will not be correct. To do this take a level that reaches across the bottom staying in between the air traps. Next use a so called pecker checker attached to your prop shaft. At this point before measuring make certain your engine is "set up" meaning clamps are tight, and it is down on the transom or shim sticks. The steering can be hooked up if you wish. Now take that level and move it forward (front of boat) to roughly the end of the checker. Measure from the top side of the level down to your checker. If your short term memory is shaky, right this number down. BE ACCURATE as 1/8" can make a big difference, real big. Next move your level as close to the rear of the boat as possible and measure from the top of the level to your checker. Again, write this down if needed. Once you have these two numbers, you can subtract to arrive at your final number. If the front of the checker measures a larger number than the rear it means you are "tucked out" If the rear number is larger than the front number you are "tucked in". I encourage and plead with you to write this measurement down. And be consistent on where you measure. It makes for fewer mistakes in some quick decisions. Adjust your brackets as necessary to achieve the number you want.
If you want to measure your prop shaft height, simply take a longer level and lay it on the actual bottom of the boat. On most prop shafts there is a small hole in the very center of it at the rear. This is where it was in lathe being turned. It is a center point. Keeping your level tight to the bottom measure from the top edge of the level to that center point at the rear of the prop shaft. This is your height.
As I said this is a starting point. I have found this measurement to be a great place to start each new hydro I have built and tested. To change set-ups it will depend on your hull design and props and power bands. There is no what works best for Brian Palmquist will work for Darren Goehrig.
One important tip. If you think running above the bottom of the boat works, be certain the gearbox you choose to run will handle this. Not only is water important to cool your engine, but you need to control the boat in the corners too. My fastest set-up will achieve 4 - 5 MPH faster than my actual race set-up. Race set-up means it will handle everywhere on the race course without fearing of losing control in rougher water. I will always give up speed for control.
At any rate, this is bound to get several different opinions and it should. Each boat is different. Your weight and the power band of your engine all play a role.
Here are some basics assuming you understand the basic terminology.
For the larger hydros, kneeling and not laying down. I am thinking 750CCMH (44CI) and 850CCMH (3 Holer or SEH).
A decent starting point for an average adult on a somewhat recent hull that has not gained weight, and is of the designer’s original plan.
Set the engine up with a 1/8" Tucked under measurement. Also start out with he center of the prop shaft roughly 1/2" below the bottom of the ACTUAL bottom of the boat. Do NOT measure this from inside the tunnel of the boat. Your measurement will not be correct. To do this take a level that reaches across the bottom staying in between the air traps. Next use a so called pecker checker attached to your prop shaft. At this point before measuring make certain your engine is "set up" meaning clamps are tight, and it is down on the transom or shim sticks. The steering can be hooked up if you wish. Now take that level and move it forward (front of boat) to roughly the end of the checker. Measure from the top side of the level down to your checker. If your short term memory is shaky, right this number down. BE ACCURATE as 1/8" can make a big difference, real big. Next move your level as close to the rear of the boat as possible and measure from the top of the level to your checker. Again, write this down if needed. Once you have these two numbers, you can subtract to arrive at your final number. If the front of the checker measures a larger number than the rear it means you are "tucked out" If the rear number is larger than the front number you are "tucked in". I encourage and plead with you to write this measurement down. And be consistent on where you measure. It makes for fewer mistakes in some quick decisions. Adjust your brackets as necessary to achieve the number you want.
If you want to measure your prop shaft height, simply take a longer level and lay it on the actual bottom of the boat. On most prop shafts there is a small hole in the very center of it at the rear. This is where it was in lathe being turned. It is a center point. Keeping your level tight to the bottom measure from the top edge of the level to that center point at the rear of the prop shaft. This is your height.
As I said this is a starting point. I have found this measurement to be a great place to start each new hydro I have built and tested. To change set-ups it will depend on your hull design and props and power bands. There is no what works best for Brian Palmquist will work for Darren Goehrig.
One important tip. If you think running above the bottom of the boat works, be certain the gearbox you choose to run will handle this. Not only is water important to cool your engine, but you need to control the boat in the corners too. My fastest set-up will achieve 4 - 5 MPH faster than my actual race set-up. Race set-up means it will handle everywhere on the race course without fearing of losing control in rougher water. I will always give up speed for control.
At any rate, this is bound to get several different opinions and it should. Each boat is different. Your weight and the power band of your engine all play a role.
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