Donzi 24 -2000
06-18-2023, 09:16 AM
#1
Donzi 24 -2000
Hello guys,
I´m from Sweden and this is my first boat. I don´t know much about boats so I would be grateful for some expert advice.
I have a 350 Mag MPI 300 engine on the boat but can only reach around 35 knots(I don´t know what this translates to in MPH). Do anyone of you guys have any suggestions how to make it go faster? I have tried to speak to different "experts" but they all give me different answers and I feel really lost..
Thank you guys!
I´m from Sweden and this is my first boat. I don´t know much about boats so I would be grateful for some expert advice.
I have a 350 Mag MPI 300 engine on the boat but can only reach around 35 knots(I don´t know what this translates to in MPH). Do anyone of you guys have any suggestions how to make it go faster? I have tried to speak to different "experts" but they all give me different answers and I feel really lost..
Thank you guys!
06-18-2023, 08:03 PM
#2
Gold Member
Gold Member
Welcome to oso!
Tell us more about your boat and I’m sure you’ll get some good replies.
24’ Donzi…..what model is it?
Is the engine strong, good compression, and tuned properly?
What maximum rpm are you getting?
Is the drive unit an Alpha or Bravo?
What propellor and pitch do you have?
Many boats in Sweden have antifoul (bottom paint) which knocks off a lot of speed too.
More info and some knowledgeable members will jump in.
RR
P.S. 35 knots is 40 mph.
Tell us more about your boat and I’m sure you’ll get some good replies.
24’ Donzi…..what model is it?
Is the engine strong, good compression, and tuned properly?
What maximum rpm are you getting?
Is the drive unit an Alpha or Bravo?
What propellor and pitch do you have?
Many boats in Sweden have antifoul (bottom paint) which knocks off a lot of speed too.
More info and some knowledgeable members will jump in.
RR
P.S. 35 knots is 40 mph.
Last edited by rak rua; 06-18-2023 at 08:05 PM.
06-18-2023, 11:45 PM
#3
Thank you for your reply.
It is a Donzi 24 BlackWidow from year 2000.
I can not say if the motor is strong, good compression or tuned properly. Also I don´t know about the Alpha or Bravo, and the bottom color. I have tried and asked the seller but he does not reply. I will try and find someone that can help me answer those questions. The only thing I can answer is that the propeller is aluminum and the RPM on full throttle is around 5000 RPM. I´m looking for some not to expensive fixes to try and make the boat faster. I bought the boat and promised my son that it would go faster then his friends boat but now it is the opposite and my son is very disappointed with me..
I have decided to sign up for a boat mechanic course to try and learn more about boats but the mountain feels high and I´m a slow learner.
Thank you for helping me!
It is a Donzi 24 BlackWidow from year 2000.
I can not say if the motor is strong, good compression or tuned properly. Also I don´t know about the Alpha or Bravo, and the bottom color. I have tried and asked the seller but he does not reply. I will try and find someone that can help me answer those questions. The only thing I can answer is that the propeller is aluminum and the RPM on full throttle is around 5000 RPM. I´m looking for some not to expensive fixes to try and make the boat faster. I bought the boat and promised my son that it would go faster then his friends boat but now it is the opposite and my son is very disappointed with me..
I have decided to sign up for a boat mechanic course to try and learn more about boats but the mountain feels high and I´m a slow learner.
Thank you for helping me!
06-19-2023, 02:18 AM
#4
Gold Member
Gold Member
I’m not a Donzi expert but I thought the Black Widow was earlier than 2000. I thought they were around 1990?
Check the HIN (hull identification number) might be on your paperwork, but should be a 17 character number on the back of the hull. Right hand side, just below the gunnel rubbing strip. The last two characters will tell you the year. ‘00’ would be a 2000 model, ‘95’ means 1995 model, ‘90’ means 1990 model etc, etc.
I thought most of them were built with an OMC big block engine, 454 cubic inch Chevrolet block, a couple of different versions, 330 hp or about 370 hp. The 350 magnum 300 hp is a good engine but sounds like it may not be the original engine. Doesn’t matter, Mercruiser engines are probably a lot easier for any accessory parts and service in Sweden anyway. 🙂
With the bigger 330-370hp engines, I think they did around 60 mph when new. Speed will be less if the boat is heavy, full of fuel, a lot of gear and people on board or the bottom of the hull is not clean. With most boats that age, there’s also a risk the stringers and transom have water intrusion and the wood inside is waterlogged. That can add a lot of weight to a boat. Did anyone survey or inspect the boat when you were buying it? The aluminum prop won’t help, not sure what size you’d need but a good stainless steel prop will be faster.
Driving the boat takes time to learn how to get the best performance. Accelerate gradually with trim tabs down (if you have them) and the sterndrive down (in). Once up and running at 25 knots, you should raise the trim tabs all the way up and trim the sterndrive up a little to lift the boat up and reduce the amount of hull touching the water. Check on the trim gauge while the boat is out of the water, look where the gauge reads when the drive is vertical, that’s a good place to start once you’re up on the plane. You can gradually trim the drive up a little bit more but the aluminium prop will cavitate (slip) pretty easily. A stainless prop will bite and hold on much better. It’s a lot of learning, just go slowly and enjoy yourself. If the boat feels unstable, starts to bounce or react strangely, you’re pushing too hard.
Try a Google search for Black Widow 24 speed and you’ll find info on other forums. I’m sure someone else will jump in here too, when they wake up. Most of our oso members are based in America. 🙂
Sorry it’s not as fast as your son hopes but it should be a bit quicker than 35 knots of the engine is running well, it’s not too heavy and you get a better prop. Meantime, remind him that although his mate’s boat is faster, a Donzi is probably a lot cooler. 😎
Good luck,
RR
Check the HIN (hull identification number) might be on your paperwork, but should be a 17 character number on the back of the hull. Right hand side, just below the gunnel rubbing strip. The last two characters will tell you the year. ‘00’ would be a 2000 model, ‘95’ means 1995 model, ‘90’ means 1990 model etc, etc.
I thought most of them were built with an OMC big block engine, 454 cubic inch Chevrolet block, a couple of different versions, 330 hp or about 370 hp. The 350 magnum 300 hp is a good engine but sounds like it may not be the original engine. Doesn’t matter, Mercruiser engines are probably a lot easier for any accessory parts and service in Sweden anyway. 🙂
With the bigger 330-370hp engines, I think they did around 60 mph when new. Speed will be less if the boat is heavy, full of fuel, a lot of gear and people on board or the bottom of the hull is not clean. With most boats that age, there’s also a risk the stringers and transom have water intrusion and the wood inside is waterlogged. That can add a lot of weight to a boat. Did anyone survey or inspect the boat when you were buying it? The aluminum prop won’t help, not sure what size you’d need but a good stainless steel prop will be faster.
Driving the boat takes time to learn how to get the best performance. Accelerate gradually with trim tabs down (if you have them) and the sterndrive down (in). Once up and running at 25 knots, you should raise the trim tabs all the way up and trim the sterndrive up a little to lift the boat up and reduce the amount of hull touching the water. Check on the trim gauge while the boat is out of the water, look where the gauge reads when the drive is vertical, that’s a good place to start once you’re up on the plane. You can gradually trim the drive up a little bit more but the aluminium prop will cavitate (slip) pretty easily. A stainless prop will bite and hold on much better. It’s a lot of learning, just go slowly and enjoy yourself. If the boat feels unstable, starts to bounce or react strangely, you’re pushing too hard.
Try a Google search for Black Widow 24 speed and you’ll find info on other forums. I’m sure someone else will jump in here too, when they wake up. Most of our oso members are based in America. 🙂
Sorry it’s not as fast as your son hopes but it should be a bit quicker than 35 knots of the engine is running well, it’s not too heavy and you get a better prop. Meantime, remind him that although his mate’s boat is faster, a Donzi is probably a lot cooler. 😎
Good luck,
RR
06-19-2023, 03:04 AM
#5
I’m not a Donzi expert but I thought the Black Widow was earlier than 2000. I thought they were around 1990?
Check the HIN (hull identification number) might be on your paperwork, but should be a 17 character number on the back of the hull. Right hand side, just below the gunnel rubbing strip. The last two characters will tell you the year. ‘00’ would be a 2000 model, ‘95’ means 1995 model, ‘90’ means 1990 model etc, etc.
I thought most of them were built with an OMC big block engine, 454 cubic inch Chevrolet block, a couple of different versions, 330 hp or about 370 hp. The 350 magnum 300 hp is a good engine but sounds like it may not be the original engine. Doesn’t matter, Mercruiser engines are probably a lot easier for any accessory parts and service in Sweden anyway. 🙂
With the bigger 330-370hp engines, I think they did around 60 mph when new. Speed will be less if the boat is heavy, full of fuel, a lot of gear and people on board or the bottom of the hull is not clean. With most boats that age, there’s also a risk the stringers and transom have water intrusion and the wood inside is waterlogged. That can add a lot of weight to a boat. Did anyone survey or inspect the boat when you were buying it? The aluminum prop won’t help, not sure what size you’d need but a good stainless steel prop will be faster.
Driving the boat takes time to learn how to get the best performance. Accelerate gradually with trim tabs down (if you have them) and the sterndrive down (in). Once up and running at 25 knots, you should raise the trim tabs all the way up and trim the sterndrive up a little to lift the boat up and reduce the amount of hull touching the water. Check on the trim gauge while the boat is out of the water, look where the gauge reads when the drive is vertical, that’s a good place to start once you’re up on the plane. You can gradually trim the drive up a little bit more but the aluminium prop will cavitate (slip) pretty easily. A stainless prop will bite and hold on much better. It’s a lot of learning, just go slowly and enjoy yourself. If the boat feels unstable, starts to bounce or react strangely, you’re pushing too hard.
Try a Google search for Black Widow 24 speed and you’ll find info on other forums. I’m sure someone else will jump in here too, when they wake up. Most of our oso members are based in America. 🙂
Sorry it’s not as fast as your son hopes but it should be a bit quicker than 35 knots of the engine is running well, it’s not too heavy and you get a better prop. Meantime, remind him that although his mate’s boat is faster, a Donzi is probably a lot cooler. 😎
Good luck,
RR
Check the HIN (hull identification number) might be on your paperwork, but should be a 17 character number on the back of the hull. Right hand side, just below the gunnel rubbing strip. The last two characters will tell you the year. ‘00’ would be a 2000 model, ‘95’ means 1995 model, ‘90’ means 1990 model etc, etc.
I thought most of them were built with an OMC big block engine, 454 cubic inch Chevrolet block, a couple of different versions, 330 hp or about 370 hp. The 350 magnum 300 hp is a good engine but sounds like it may not be the original engine. Doesn’t matter, Mercruiser engines are probably a lot easier for any accessory parts and service in Sweden anyway. 🙂
With the bigger 330-370hp engines, I think they did around 60 mph when new. Speed will be less if the boat is heavy, full of fuel, a lot of gear and people on board or the bottom of the hull is not clean. With most boats that age, there’s also a risk the stringers and transom have water intrusion and the wood inside is waterlogged. That can add a lot of weight to a boat. Did anyone survey or inspect the boat when you were buying it? The aluminum prop won’t help, not sure what size you’d need but a good stainless steel prop will be faster.
Driving the boat takes time to learn how to get the best performance. Accelerate gradually with trim tabs down (if you have them) and the sterndrive down (in). Once up and running at 25 knots, you should raise the trim tabs all the way up and trim the sterndrive up a little to lift the boat up and reduce the amount of hull touching the water. Check on the trim gauge while the boat is out of the water, look where the gauge reads when the drive is vertical, that’s a good place to start once you’re up on the plane. You can gradually trim the drive up a little bit more but the aluminium prop will cavitate (slip) pretty easily. A stainless prop will bite and hold on much better. It’s a lot of learning, just go slowly and enjoy yourself. If the boat feels unstable, starts to bounce or react strangely, you’re pushing too hard.
Try a Google search for Black Widow 24 speed and you’ll find info on other forums. I’m sure someone else will jump in here too, when they wake up. Most of our oso members are based in America. 🙂
Sorry it’s not as fast as your son hopes but it should be a bit quicker than 35 knots of the engine is running well, it’s not too heavy and you get a better prop. Meantime, remind him that although his mate’s boat is faster, a Donzi is probably a lot cooler. 😎
Good luck,
RR
06-19-2023, 06:41 AM
#6
Registered
Please post a couple of pictures of this boat, and a picture of the engine. That might be helpful in getting some additional answers to your questions.
06-20-2023, 09:43 AM
#7
Thanks! RPM is 5200 on max throttle. No great difference in speed between 4000 and 5200. One of the ”things” that I hold my hand on is much cooler then the other.
ps. I have problem uploading images. It says I’m not allowed to have url’s in my post…?
06-20-2023, 09:45 AM
#8
06-20-2023, 10:57 AM
#9
Registered
06-20-2023, 01:39 PM
#10
