Dumas Deep Vee 40

[dwilfong]

well hear it is.

 

[dwilfong]

well hear it is.

First day on the water boat spent more time upside down then I would like. Full throttle runs ended up with total catastrophe. Tried to adjust stinger but went to far and boat began to porpoise. Re-adjusted again a few times until I got the boat stable...somewhat. Still full speed runs ended up with blow over. I think I learned a good lesson in CG. Thank God I had the 2 rudders so I could turn in either direction to avoid crashing. All in all not too bad for a first time boater running a boat for the first time.

Seem like at high speed the only thing in the water was the prop and the rudders. Corners real well and can do a full throttle through corner but as soon as you come out it goes air borne....I mean lots of air, like 5-6 feet. What a blast!!!!!

 

[jetpack]

Congrats on the build! Looks like you're having fun, and good to see some experimentation! It's the only way to learn and get a good picture that sticks with you.

A sport boat can have two rudders, and if you're making left and right turns with it, you should. That is why they are made. Especially on a deep vee design that lay way over when turning. You won't know the difference between one rudder or two on speed unless your tiller arm adjustment across the two is off. They are pretty much transparent on drag otherwise, and in my opinion, if your running clear out of the water you need them!

Sounds like a little nose weight wouldn't be a bad idea! Also try adjusting the angle front to back with the rudder plate, it might calm it down a little out of the corners.

 

[dwilfong]

Congrats on the build! Looks like you're having fun, and good to see some experimentation! It's the only way to learn and get a good picture that sticks with you.
A sport boat can have two rudders, and if you're making left and right turns with it, you should. That is why they are made. Especially on a deep vee design that lay way over when turning. You won't know the difference between one rudder or two on speed unless your tiller arm adjustment across the two is off. They are pretty much transparent on drag otherwise, and in my opinion, if your running clear out of the water you need them!

Sounds like a little nose weight wouldn't be a bad idea! Also try adjusting the angle front to back with the rudder plate, it might calm it down a little out of the corners.

The two rudders and the prop are the only thing in the water at speed. I think that if I remove one it would not stay right side up with out trim tabs.

The prop I am using is a Octura x452/3 with the tongue removed. I am not to sure how much lift this prop has. Would a different prop put more boat in the water and make it more stable.

 

[jetpack]

Yes, it would.

X series props are medium lift and usually used for surface drive. With it being a 3 blade even more.

If you switched to a 12 to 14 series, it would probably handle a bit better with it being a low lift, submerged drive prop.

If your RPM's seem about right with what you have right now, going to the same size in a 12 series with two blades might keep it right where its at.

Here's where it would be great for you to have a club around, and ask to swap some props around with other boaters for testing. Otherwise it is trial and error with the wallet.

 

[dwilfong]

Yes, it would.
X series props are medium lift and usually used for surface drive. With it being a 3 blade even more.

If you switched to a 12 to 14 series, it would probably handle a bit better with it being a low lift, submerged drive prop.

If your RPM's seem about right with what you have right now, going to the same size in a 12 series with two blades might keep it right where its at.

Here's where it would be great for you to have a club around, and ask to swap some props around with other boaters for testing. Otherwise it is trial and error with the wallet.

Yes it would be nice to have some one to run with to learn the ropes. To this point I have bin on my own except for the grate help of the people on this sight. It is hard when you work in Miami all week and go home to Orlando on the weekends. The club in Orlando lost their lake and they run gas boats. Would like to find some one running nitro near Orlando. I live on the boggy creek in kissimme so I can take my big boat out to east lake toho and lanch from myboat. makes it a lot easier when you launch from the chase boat just drive over to it when it flips dump out the water and go again.

 

[dwilfong]

Yes, it would.
X series props are medium lift and usually used for surface drive. With it being a 3 blade even more.

If you switched to a 12 to 14 series, it would probably handle a bit better with it being a low lift, submerged drive prop.

If your RPM's seem about right with what you have right now, going to the same size in a 12 series with two blades might keep it right where its at.

Here's where it would be great for you to have a club around, and ask to swap some props around with other boaters for testing. Otherwise it is trial and error with the wallet.

Yes it would be nice to have some one to run with to learn the ropes. To this point I have bin on my own except for the grate help of the people on this sight. It is hard when you work in Miami all week and go home to Orlando on the weekends. The club in Orlando lost their lake and they run gas boats. Would like to find some one running nitro near Orlando. I live on the boggy creek in kissimme so I can take my big boat out to east lake toho and lanch from myboat. makes it a lot easier when you launch from the chase boat just drive over to it when it flips dump out the water and go again.

went out on the lake today boat ran more stable, added weight to front of boat CG at 33%. Tried adjusting right rudder forward and left back. This took out most of the roll to right out. The twin rudder setup worked just like I had planed. Will make More adj. by adding washers to rudder mount. Still don't know how fast it can go. The boat still out of water at full throttle. Have not found RPM limit of Eng. Set up Eng using marty's soft wear for 28000 RPM's and 60% nitro. I am thinking I need more weight boat weights 7.6 lbs. without fuel now and you can't goosed the throttle or it comes out of the water and tail walks.

 

[dwilfong]

Yes, it would.
X series props are medium lift and usually used for surface drive. With it being a 3 blade even more.

If you switched to a 12 to 14 series, it would probably handle a bit better with it being a low lift, submerged drive prop.

If your RPM's seem about right with what you have right now, going to the same size in a 12 series with two blades might keep it right where its at.

Here's where it would be great for you to have a club around, and ask to swap some props around with other boaters for testing. Otherwise it is trial and error with the wallet.

Yes it would be nice to have some one to run with to learn the ropes. To this point I have bin on my own except for the grate help of the people on this sight. It is hard when you work in Miami all week and go home to Orlando on the weekends. The club in Orlando lost their lake and they run gas boats. Would like to find some one running nitro near Orlando. I live on the boggy creek in kissimme so I can take my big boat out to east lake toho and lanch from myboat. makes it a lot easier when you launch from the chase boat just drive over to it when it flips dump out the water and go again.

went out on the lake today boat ran more stable, added weight to front of boat CG at 33%. Tried adjusting right rudder forward and left back. This took out most of the roll to right out. The twin rudder setup worked just like I had planed. Will make More adj. by adding washers to rudder mount. Still don't know how fast it can go. The boat still out of water at full throttle. Have not found RPM limit of Eng. Set up Eng using marty's soft wear for 28000 RPM's and 60% nitro. I am thinking I need more weight boat weights 7.6 lbs. without fuel now and you can't goosed the throttle or it comes out of the water and tail walks.

hear are some pics of my finshed boat.

 

[jetpack]

You found improvements. That's great. Why not try easing down the nitro? 60% is getting way up there. If you backed down the nitro to say 30%, it would be cheaper by far, probably be able to keep it wide open, and then you'll have a stable top end rpm to judge your changes better, plus be easier on the motor until the handling is shook out a bit better?

Adding weight isn't necessarily a bad thing if you have power, and if the boat needs it then you more or less have to add it if your at the end of your trimming limits to counter-act the air lift of the hull.

 

[dwilfong]

You found improvements. That's great. Why not try easing down the nitro? 60% is getting way up there. If you backed down the nitro to say 30%, it would be cheaper by far, probably be able to keep it wide open, and then you'll have a stable top end rpm to judge your changes better, plus be easier on the motor until the handling is shook out a bit better?
Adding weight isn't necessarily a bad thing if you have power, and if the boat needs it then you more or less have to add it if your at the end of your trimming limits to counter-act the air lift of the hull.

I was thinking of lowering the nitro. The eng is running very strong and has more response and power than this small boat can handle.

I ported out the case and sleeve to have the same cross section as the opening in the sleeve. I have also cut the skirt off the piston that is below the sleeve at BDC except what is needed to cover ex. port.

I disassemble the eng after every test run to check piston fit and condition of piston top and head button. So far no pitting of chamber or piston.

Squash clearance set at .011 and CR is 8.8 with stock button and sleeve shimmed .010 to 187 deg. ex timing.

Also used devcon to make ramp in drum valve. Using a K&B .453 disk idle jet carb.

I know I am new to all this but this K&B I have put together with bits and pieces seam's to run very strong. Have about $160 into this eng not to bad for a junk yard dog Kick Bucket !!!!!!!!

 

[dwilfong]

You found improvements. That's great. Why not try easing down the nitro? 60% is getting way up there. If you backed down the nitro to say 30%, it would be cheaper by far, probably be able to keep it wide open, and then you'll have a stable top end rpm to judge your changes better, plus be easier on the motor until the handling is shook out a bit better?
Adding weight isn't necessarily a bad thing if you have power, and if the boat needs it then you more or less have to add it if your at the end of your trimming limits to counter-act the air lift of the hull.

I was thinking of lowering the nitro. The eng is running very strong and has more response and power than this small boat can handle.

I ported out the case and sleeve to have the same cross section as the opening in the sleeve. I have also cut the skirt off the piston that is below the sleeve at BDC except what is needed to cover ex. port.

I disassemble the eng after every test run to check piston fit and condition of piston top and head button. So far no pitting of chamber or piston.

Squash clearance set at .011 and CR is 8.8 with stock button and sleeve shimmed .010 to 187 deg. ex timing.

Also used devcon to make ramp in drum valve. Using a K&B .453 disk idle jet carb.

I know I am new to all this but this K&B I have put together with bits and pieces seam's to run very strong. Have about $160 into this eng not to bad for a junk yard dog Kick Bucket !!!!!!!!

Tried something new to day put a spoiler on boat NASCAR style and it worked!! Boat stable at high speed can hold full throttle all the way in corners and down straight.What a feeling seeing boat go fast and steady. Tried 1455/3 prop and P235 prop but went back to X452/3 likes this prop. Got the needle set running very strong. This thing flies!!!! Going by my calculations 28000 RPM and the prop pitch some wear between 60-65 MPH.

Posting some pics. of new setup.

 

[dwilfong]

You found improvements. That's great. Why not try easing down the nitro? 60% is getting way up there. If you backed down the nitro to say 30%, it would be cheaper by far, probably be able to keep it wide open, and then you'll have a stable top end rpm to judge your changes better, plus be easier on the motor until the handling is shook out a bit better?
Adding weight isn't necessarily a bad thing if you have power, and if the boat needs it then you more or less have to add it if your at the end of your trimming limits to counter-act the air lift of the hull.

I was thinking of lowering the nitro. The eng is running very strong and has more response and power than this small boat can handle.

I ported out the case and sleeve to have the same cross section as the opening in the sleeve. I have also cut the skirt off the piston that is below the sleeve at BDC except what is needed to cover ex. port.

I disassemble the eng after every test run to check piston fit and condition of piston top and head button. So far no pitting of chamber or piston.

Squash clearance set at .011 and CR is 8.8 with stock button and sleeve shimmed .010 to 187 deg. ex timing.

Also used devcon to make ramp in drum valve. Using a K&B .453 disk idle jet carb.

I know I am new to all this but this K&B I have put together with bits and pieces seam's to run very strong. Have about $160 into this eng not to bad for a junk yard dog Kick Bucket !!!!!!!!

Tried something new to day put a spoiler on boat NASCAR style and it worked!! Boat stable at high speed can hold full throttle all the way in corners and down straight.What a feeling seeing boat go fast and steady. Tried 1455/3 prop and P235 prop but went back to X452/3 likes this prop. Got the needle set running very strong. This thing flies!!!! Going by my calculations 28000 RPM and the prop pitch some wear between 60-65 MPH.

Posting some pics. of new setup.

Did have one minor problem lost pipe in last crash. Going to shop to get new one. This time I will put some clamps on coupler. Live and learn!

 

[dwilfong]

You found improvements. That's great. Why not try easing down the nitro? 60% is getting way up there. If you backed down the nitro to say 30%, it would be cheaper by far, probably be able to keep it wide open, and then you'll have a stable top end rpm to judge your changes better, plus be easier on the motor until the handling is shook out a bit better?
Adding weight isn't necessarily a bad thing if you have power, and if the boat needs it then you more or less have to add it if your at the end of your trimming limits to counter-act the air lift of the hull.

I was thinking of lowering the nitro. The eng is running very strong and has more response and power than this small boat can handle.

I ported out the case and sleeve to have the same cross section as the opening in the sleeve. I have also cut the skirt off the piston that is below the sleeve at BDC except what is needed to cover ex. port.

I disassemble the eng after every test run to check piston fit and condition of piston top and head button. So far no pitting of chamber or piston.

Squash clearance set at .011 and CR is 8.8 with stock button and sleeve shimmed .010 to 187 deg. ex timing.

Also used devcon to make ramp in drum valve. Using a K&B .453 disk idle jet carb.

I know I am new to all this but this K&B I have put together with bits and pieces seam's to run very strong. Have about $160 into this eng not to bad for a junk yard dog Kick Bucket !!!!!!!!

Tried something new to day put a spoiler on boat NASCAR style and it worked!! Boat stable at high speed can hold full throttle all the way in corners and down straight.What a feeling seeing boat go fast and steady. Tried 1455/3 prop and P235 prop but went back to X452/3 likes this prop. Got the needle set running very strong. This thing flies!!!! Going by my calculations 28000 RPM and the prop pitch some wear between 60-65 MPH.

Posting some pics. of new setup.

Did have one minor problem lost pipe in last crash. Going to shop to get new one. This time I will put some clamps on coupler. Live and learn!

well could not get boat to stay in water at top speed with new prop AB 5077/B thats one bad prop. So I tried some thing new took all the Jewry of the back of the boat. (Did wonders for CG) Cut down the stinger and got shorter rudder set back.

Trimming the boat is a lot easier with the prop closer to the boat doesn't seam to want to lift boat out of water. getting closer to 6 laps around my make shift course with out complete disaster.

Would like to try racing at Melbourne next month.

Some pics of new setup.