Dauntless 17 Porpoises and Slow Acceleration

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Author Topic:   Dauntless 17 Porpoises and Slow Acceleration

Steve Widmer posted 05-29-2008 08:40 AM ET (US)
I have a Dauntless 17 with the dual console arrangement that is now the Venture model style. It has a Johnson 115-HP Ocean Runner. The boat takes longer than I'd like to [accelerate from a standing start to plane]. I also have a problem when I trim out the motor, not even very far. The [DAUNTLESS 17] wants to porpoise [a repeated oscillation of the bow going up and down], and I have to trim [the motor] way down or slow down and go again. I've been thinking of putting on an aqua foil. Any comments or suggestions?
Tom W Clark posted 05-29-2008 09:17 AM ET (US)
A good propeller can have a huge effect on how your boat runs. Exactly what propeller are you using now?
jimh posted 05-29-2008 09:43 PM ET (US)
Also tell us about the engine mounting height in the current set up.
2manyboats posted 05-29-2008 10:51 PM ET (US)
Does your hull have the notch at the bottom of the transom?
joeyuniz posted 05-29-2008 11:10 PM ET (US)
I had a Dauntless 17 [dual console] with a 1996 Johnson 112-HP that [also had slow acceleration and porpoised]. I put a Doel-Fin [anti-ventilation plate foil appendage] on [the motor] and it helped [reduce the problems with the acceleration and porpoising] dramatically. I also noticed that with five people on the boat it was best to move some people to the bow [to allow the boat to] plane faster. The Dauntless was never really a good planing boat due to how far back the windshield and seating are. Also the boat doesn't have a notch at the bottom. My boat had a 17-inch aluminum propeller and I could achieve 42-MPH. I believe less fuel and a stainless performance propeller would [have] helped a lot.
Jefecinco posted 05-30-2008 09:08 AM ET (US)
Steve,
I have a 1999 Dauntless 16 with the hull notch powered by a 115 HP FICHT. I had similar problems, [that is, poor acceleration and a tendency to porpoise]. I first attempted to overcome poor [acceleration from a standing start] by installing a Stingray hydrofoil stabilizer. It provided a degree of improvement but I remained unsatisfied. I then sought advice on this forum, and, after a number of replies, I decided to change my propeller to a four-blade 13-1/4 X 15 Stiletto Bay I. Tom Clark was kind enough to recommend the propeller and to sell me one at a very reasonable price.
I feel that I now have exceptionally good performance from combination of the boat, the load, the engine, and the propeller. The hydrofoil stabilizer remains in place. I suspect that removing it would not harm performance but I've been to busy and lazy to try it.
I recommend you seek the correct propeller for your performance needs. I don't recommend a hydrofoil to correct your problem. It just does too little to be meaningful in my opinion.
Butch
jimh posted 05-30-2008 08:30 PM ET (US)
On a 17-foot boat, the weight of five people is a very significant variation in the total weight of the boat, so it is not surprising at all that the performance of a 17-foot boat will vary when loaded with five people compared to when only one is aboard. This is really a characteristic of all boats: performance is closely related to weight.
Boats which are stern heavy are more difficult to transition to plane. Distribution of weight will help a boat get on plane faster. Keep weight out of the extreme ends of the boat. When transitioning to plane there is a tendency for the stern of the boat to squat down, and if there is extra weight in the stern this tendency is exaggerated, possibly to the point where the boat can not climb out of the hole in the water thus created.
Jefecinco posted 05-31-2008 09:37 AM ET (US)
Indeed, trim is a huge factor on the small Dauntless hulls. On the latest outing on my 16 it was windy with the expected rough water in the open bay. The heaviest of our fishing trio normally rides forward on the cooler seat ahead of the console. The boat is perfect with him up there. However, as he was getting pretty well soaked he moved aft to just behind the console seat for some protection. I was very surprised at how the boats attitude, and speed was affected. At the same throttle setting the boat was wallowing and soon came off plane and simply plowed. I had to apply a lot of throttle and lower the engine trim in order to plane at about 4000 RPM. He is a fairly large guy at about 230 pounds but I didn't expect quite as much reaction as we experienced.
Butch
sitotis posted 06-06-2008 12:48 AM ET (US)
I had a Dauntless 17 dual console. It had a four blade stainless OMC shooter prop. It would porpoise before I put a Stingray fin on it. The Stingray made a huge difference, improving time to plane, allowing a slower speed to hold a plane, and the ability to bury the bow into a chop. It was the best, most significant improvement I made to the boat especially for the reasonably low cost.

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Author	Topic: Dauntless 17 Porpoises and Slow Acceleration
Steve Widmer	posted 05-29-2008 08:40 AM ET (US) I have a Dauntless 17 with the dual console arrangement that is now the Venture model style. It has a Johnson 115-HP Ocean Runner. The boat takes longer than I'd like to [accelerate from a standing start to plane]. I also have a problem when I trim out the motor, not even very far. The [DAUNTLESS 17] wants to porpoise [a repeated oscillation of the bow going up and down], and I have to trim [the motor] way down or slow down and go again. I've been thinking of putting on an aqua foil. Any comments or suggestions?
Tom W Clark	posted 05-29-2008 09:17 AM ET (US) A good propeller can have a huge effect on how your boat runs. Exactly what propeller are you using now?
jimh	posted 05-29-2008 09:43 PM ET (US) Also tell us about the engine mounting height in the current set up.
2manyboats	posted 05-29-2008 10:51 PM ET (US) Does your hull have the notch at the bottom of the transom?
joeyuniz	posted 05-29-2008 11:10 PM ET (US) I had a Dauntless 17 [dual console] with a 1996 Johnson 112-HP that [also had slow acceleration and porpoised]. I put a Doel-Fin [anti-ventilation plate foil appendage] on [the motor] and it helped [reduce the problems with the acceleration and porpoising] dramatically. I also noticed that with five people on the boat it was best to move some people to the bow [to allow the boat to] plane faster. The Dauntless was never really a good planing boat due to how far back the windshield and seating are. Also the boat doesn't have a notch at the bottom. My boat had a 17-inch aluminum propeller and I could achieve 42-MPH. I believe less fuel and a stainless performance propeller would [have] helped a lot.
Jefecinco	posted 05-30-2008 09:08 AM ET (US) Steve, I have a 1999 Dauntless 16 with the hull notch powered by a 115 HP FICHT. I had similar problems, [that is, poor acceleration and a tendency to porpoise]. I first attempted to overcome poor [acceleration from a standing start] by installing a Stingray hydrofoil stabilizer. It provided a degree of improvement but I remained unsatisfied. I then sought advice on this forum, and, after a number of replies, I decided to change my propeller to a four-blade 13-1/4 X 15 Stiletto Bay I. Tom Clark was kind enough to recommend the propeller and to sell me one at a very reasonable price. I feel that I now have exceptionally good performance from combination of the boat, the load, the engine, and the propeller. The hydrofoil stabilizer remains in place. I suspect that removing it would not harm performance but I've been to busy and lazy to try it. I recommend you seek the correct propeller for your performance needs. I don't recommend a hydrofoil to correct your problem. It just does too little to be meaningful in my opinion. Butch
jimh	posted 05-30-2008 08:30 PM ET (US) On a 17-foot boat, the weight of five people is a very significant variation in the total weight of the boat, so it is not surprising at all that the performance of a 17-foot boat will vary when loaded with five people compared to when only one is aboard. This is really a characteristic of all boats: performance is closely related to weight. Boats which are stern heavy are more difficult to transition to plane. Distribution of weight will help a boat get on plane faster. Keep weight out of the extreme ends of the boat. When transitioning to plane there is a tendency for the stern of the boat to squat down, and if there is extra weight in the stern this tendency is exaggerated, possibly to the point where the boat can not climb out of the hole in the water thus created.
Jefecinco	posted 05-31-2008 09:37 AM ET (US) Indeed, trim is a huge factor on the small Dauntless hulls. On the latest outing on my 16 it was windy with the expected rough water in the open bay. The heaviest of our fishing trio normally rides forward on the cooler seat ahead of the console. The boat is perfect with him up there. However, as he was getting pretty well soaked he moved aft to just behind the console seat for some protection. I was very surprised at how the boats attitude, and speed was affected. At the same throttle setting the boat was wallowing and soon came off plane and simply plowed. I had to apply a lot of throttle and lower the engine trim in order to plane at about 4000 RPM. He is a fairly large guy at about 230 pounds but I didn't expect quite as much reaction as we experienced. Butch
sitotis	posted 06-06-2008 12:48 AM ET (US) I had a Dauntless 17 dual console. It had a four blade stainless OMC shooter prop. It would porpoise before I put a Stingray fin on it. The Stingray made a huge difference, improving time to plane, allowing a slower speed to hold a plane, and the ability to bury the bow into a chop. It was the best, most significant improvement I made to the boat especially for the reasonably low cost.