I'm new and recently bought an old (is there any other kind) O'Day 19' Mariner. It has a 6 h.p Evinrude outboard. The propeller doesn't propel well. Somebody offered me a propeller shaft extension (no price yet). I saw on E-bay a 28 h.p that already has an extended shaft for $75.00. Are there any pro's or con's to upping to a larger motor?
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That much larger
an engine would be excessively heavy and powerful. If you present propeller is fully submerged when it is running then the shaft is long enough. If it has only two blades you should talk to a dealer about getting a three or four blade low pitch prop. That will give you much more thrust at low speed. The engine that you have can be carried by one person. A 28hp engine would take two men and a boy to carry it..
an engine would be excessively heavy and powerful. If you present propeller is fully submerged when it is running then the shaft is long enough. If it has only two blades you should talk to a dealer about getting a three or four blade low pitch prop. That will give you much more thrust at low speed. The engine that you have can be carried by one person. A 28hp engine would take two men and a boy to carry it..
According to a friend of mine who just sold his boat, he hated the short shaft because was in the draft of the boat and caused him a lot of problems in reverse.I agree.
A 6hp for a 19 footer is about ideal. 28hp is too too much. In my limited experience, most sailboats up to 25 - 26 feet (Mac motor-sailers aside)use OBs 10hp or less. No matter how large a motor you have, your max speed will be less than 5.5 kts based on your displacement hull. The basic reason I have one is to get in and out of the slip. In addition to the prop discusion in the first reply, you should check the position of the prop with respect to the water. Keep the prop shaft as parallel to the surface as possible. You want the motor to push the stern forward not up or down.
A 6hp for a 19 footer is about ideal. 28hp is too too much. In my limited experience, most sailboats up to 25 - 26 feet (Mac motor-sailers aside)use OBs 10hp or less. No matter how large a motor you have, your max speed will be less than 5.5 kts based on your displacement hull. The basic reason I have one is to get in and out of the slip. In addition to the prop discusion in the first reply, you should check the position of the prop with respect to the water. Keep the prop shaft as parallel to the surface as possible. You want the motor to push the stern forward not up or down.
To Much
I echo what Ross says. Your transom is not probably strong enough for the weight or the thrust of a 28 HP engine. The speed of the boat is a function of its length on the water. Once you reach that speed any additional horse power is water down the drain. a 6HP should get you to your hull speed of around 5 Knots. You should use and adjustable motor mount so that you can lower and submerge the lower end into the water and be able to bring it up and tilt it out when under sail. Outboards are not a perfect setup and when you or your crew go to the bow of the boat you may cause to pull the lower end out. Also powerboat wakes and waves may cause for the lower end to come out of the water and the propeller to cavitate. I found out long time ago that it is easier to back the boat up if you let the engine swivel turning the rudder and engine at the same time. A bigger boat may benefit from a long shaft engine but it should not matter much to you. Prop pitch would be more important. Welcome to sailing. Trailerables are fun.
I echo what Ross says. Your transom is not probably strong enough for the weight or the thrust of a 28 HP engine. The speed of the boat is a function of its length on the water. Once you reach that speed any additional horse power is water down the drain. a 6HP should get you to your hull speed of around 5 Knots. You should use and adjustable motor mount so that you can lower and submerge the lower end into the water and be able to bring it up and tilt it out when under sail. Outboards are not a perfect setup and when you or your crew go to the bow of the boat you may cause to pull the lower end out. Also powerboat wakes and waves may cause for the lower end to come out of the water and the propeller to cavitate. I found out long time ago that it is easier to back the boat up if you let the engine swivel turning the rudder and engine at the same time. A bigger boat may benefit from a long shaft engine but it should not matter much to you. Prop pitch would be more important. Welcome to sailing. Trailerables are fun.
HP
I agree with the previous posters. My Catalina 25 is fine with an 8 HP Yamaha, 28 would be way too much.
I agree with the previous posters. My Catalina 25 is fine with an 8 HP Yamaha, 28 would be way too much.
Hull Speed vs HP
A displacement hull has a theoretical hull speed. Increasing HP will not gain you any more speed than that. Theoretical Hull Speed (THS)= 1.34 X sq root LWL. If your LWL is about 18', then hull speed is about 5.68 knots. If your 6hp motor gets you to that, adding additional hp will not gain you any additional speed.
A displacement hull has a theoretical hull speed. Increasing HP will not gain you any more speed than that. Theoretical Hull Speed (THS)= 1.34 X sq root LWL. If your LWL is about 18', then hull speed is about 5.68 knots. If your 6hp motor gets you to that, adding additional hp will not gain you any additional speed.
Just to add a little
I sail with an inboard diesel. All of the calculators that I have found. I am only using about 6 hp for pushing my 9000 pound 30 foot full keel sloop to just under hull speed, about six kts. I installed a ten hp engine with a 3:1 reduction gear and a 13 inch three blade prop. If I try to go faster than the ~6 kts I just dig a hole in the river.
I sail with an inboard diesel. All of the calculators that I have found. I am only using about 6 hp for pushing my 9000 pound 30 foot full keel sloop to just under hull speed, about six kts. I installed a ten hp engine with a 3:1 reduction gear and a 13 inch three blade prop. If I try to go faster than the ~6 kts I just dig a hole in the river.
GREAT BOAT!
In 1973 I bought an Oday Mariner 19.....it was the best boat! While teaching me to sail, that boat opened a whole new world of fun exploring the offshore islands, meeting fellow sailors, and literally expanding my horizons. You'll have fun with that boat. By the way, my boat had a British Seagull long shaft single cylinder....except for shearing propeller pins, she worked great.
In 1973 I bought an Oday Mariner 19.....it was the best boat! While teaching me to sail, that boat opened a whole new world of fun exploring the offshore islands, meeting fellow sailors, and literally expanding my horizons. You'll have fun with that boat. By the way, my boat had a British Seagull long shaft single cylinder....except for shearing propeller pins, she worked great.
Mariner transom only rates for 10hp
I sail a 1975 Oday Mariner 2+2 At Kerr lake in N.C. Only use a 4 stroke 2.5 eng to move her along. I had a 2hp 2 stroke I used for a while and it work fine. Bet I did not spend $5 in gas for Mariner all summer. I look at 6hp and was going to by one but it was going to take too long to get it. Mariner is only rated for about 10 hp max. I have engine mount to raise and lower the engine it keep prop in water with on problems and I do not have to drag prop when the wind is up. Only thing you get out of big engine is more weight to carry around and you burn more fuel going nowere. I also have a Bristol 28.2 at coast it only has a 20 hp inboard engine and its over powered Oday and Stuart marine corp have built thousands of Mariner 2+2 19' Smooth sailing les Reply | Print Thread
I sail a 1975 Oday Mariner 2+2 At Kerr lake in N.C. Only use a 4 stroke 2.5 eng to move her along. I had a 2hp 2 stroke I used for a while and it work fine. Bet I did not spend $5 in gas for Mariner all summer. I look at 6hp and was going to by one but it was going to take too long to get it. Mariner is only rated for about 10 hp max. I have engine mount to raise and lower the engine it keep prop in water with on problems and I do not have to drag prop when the wind is up. Only thing you get out of big engine is more weight to carry around and you burn more fuel going nowere. I also have a Bristol 28.2 at coast it only has a 20 hp inboard engine and its over powered Oday and Stuart marine corp have built thousands of Mariner 2+2 19' Smooth sailing les Reply | Print Thread
balony
Got me a sailboat (pun intended). 37 footer. Perkins 4107 rated at 30, 40, 50 h.p. depending on who you believe. Hull speed is a little over 7 knots. Balony. Once did Buffalo to Cleveland averaging 8 knots. Open that diesel up to high RPM and that sucker MOVES. Digging a hole in the water? I think not, IT'S A BOAT. Makes a heck of a bow wave. We were going to try to have someone water ski off the back once but didn't have a ski. The problem with diesels is they are like Alaskan Huskies or Malamutes. They love to run. So I say "Full Throttle" "damn the torpedo's, full speed ahead!"
Got me a sailboat (pun intended). 37 footer. Perkins 4107 rated at 30, 40, 50 h.p. depending on who you believe. Hull speed is a little over 7 knots. Balony. Once did Buffalo to Cleveland averaging 8 knots. Open that diesel up to high RPM and that sucker MOVES. Digging a hole in the water? I think not, IT'S A BOAT. Makes a heck of a bow wave. We were going to try to have someone water ski off the back once but didn't have a ski. The problem with diesels is they are like Alaskan Huskies or Malamutes. They love to run. So I say "Full Throttle" "damn the torpedo's, full speed ahead!"
Tomh I think you needto recalculate
the distance traveled. The calculator on boatdiesel.com says the best speed you can get with a 33 foot water line and 50hp is 7.7kts. Now if you had used statute mile instead of nautical miles you would see better than 8mph. Also depending on your propeller you probably use about1.7 gallons of fuel per hour at thaat speed.
the distance traveled. The calculator on boatdiesel.com says the best speed you can get with a 33 foot water line and 50hp is 7.7kts. Now if you had used statute mile instead of nautical miles you would see better than 8mph. Also depending on your propeller you probably use about1.7 gallons of fuel per hour at thaat speed.
Hull Speed vs HP
No matter how you slice it, the laws of physics are not going to change. tom h, Ross has a point about your calculations. Adding hp simply means pushing a larger wall of water, the more hp the larger the wall. I have sailed my 35' at nearly 15 knots, but that was on a run with a following sea surfing off 10' waves. That changes the dynamics completely. But flat water upwind sailing or motoring, THS is the best any displacement hull can do.
No matter how you slice it, the laws of physics are not going to change. tom h, Ross has a point about your calculations. Adding hp simply means pushing a larger wall of water, the more hp the larger the wall. I have sailed my 35' at nearly 15 knots, but that was on a run with a following sea surfing off 10' waves. That changes the dynamics completely. But flat water upwind sailing or motoring, THS is the best any displacement hull can do.
deeper is better
A long shaft will do the job and increase the effort your motor will deliver. but remember you need more than just the estension sleeve, you need the longer drive shaft and longer water pick up tubes inside. If you can get all that do it. its an easy thing to install. I used a 4 hp long shaft yahama with a power prop on mine for years and it worked great. These things are primarly designed to motor of the basin and sail. but i used mine to move a 35 footer that had draged anchor. It pused both boats back to the mooring.
A long shaft will do the job and increase the effort your motor will deliver. but remember you need more than just the estension sleeve, you need the longer drive shaft and longer water pick up tubes inside. If you can get all that do it. its an easy thing to install. I used a 4 hp long shaft yahama with a power prop on mine for years and it worked great. These things are primarly designed to motor of the basin and sail. but i used mine to move a 35 footer that had draged anchor. It pused both boats back to the mooring.
Long shaft is better
Although its been a long time since I used an outboard, the long shaft has an enormous advantage. Aside from efficiency and speed, one of the big problems with an outboard auxilliary is the following: the time you most need the outboard is when the weather turns nasty and the water gets rough. The outboard is on the very end of the long lever made by the hull of your boat, and if there are big waves, the short shaft outboard will come out of the water every time the stern comes up. The engine will roar at the lack of resistance, and may well damage itself, and you will have no propulsion when it is in the air. Try to get a long shaft, though i don't know if the conversion from a short shaft is practical/
Although its been a long time since I used an outboard, the long shaft has an enormous advantage. Aside from efficiency and speed, one of the big problems with an outboard auxilliary is the following: the time you most need the outboard is when the weather turns nasty and the water gets rough. The outboard is on the very end of the long lever made by the hull of your boat, and if there are big waves, the short shaft outboard will come out of the water every time the stern comes up. The engine will roar at the lack of resistance, and may well damage itself, and you will have no propulsion when it is in the air. Try to get a long shaft, though i don't know if the conversion from a short shaft is practical/
Way Too Much!
Not only for all of the reasons below, but the transom can't handle the torque produced by the 28 HP motor even at reduced throttle just at hull speed. Then, if you exceed this... really big problems with torque stress on the transom! BrianW
Not only for all of the reasons below, but the transom can't handle the torque produced by the 28 HP motor even at reduced throttle just at hull speed. Then, if you exceed this... really big problems with torque stress on the transom! BrianW
21 inch transom onOday Mariner
The Oday Mariner only has 21 inch tall transom from bottom of boat. If you use Adjustable Outboard Bracket you can get by with short shaft. Plus you move the outboard out of the cockpit. Smooth sailing Les
The Oday Mariner only has 21 inch tall transom from bottom of boat. If you use Adjustable Outboard Bracket you can get by with short shaft. Plus you move the outboard out of the cockpit. Smooth sailing Les
All the above and
Ok, so I am in a sour mood. But still, a 28 horse outboard for $75.00? Be sure to drain the oil completely before using it as an anchor. A not too old, good condition 25 horse motor goes for about $1200. around here. If your motor isn't pushing well, check to ensure the prop is in the water all the time. If it is, check and see if the propeller is the correct propeller for that particular motor. I had an O'Day 192 and I used a 2hp long shaft motor that I ran on it for years and years and sold it with the boat. It ran just fine. Check your prop first. Good luck. Steve
Ok, so I am in a sour mood. But still, a 28 horse outboard for $75.00? Be sure to drain the oil completely before using it as an anchor. A not too old, good condition 25 horse motor goes for about $1200. around here. If your motor isn't pushing well, check to ensure the prop is in the water all the time. If it is, check and see if the propeller is the correct propeller for that particular motor. I had an O'Day 192 and I used a 2hp long shaft motor that I ran on it for years and years and sold it with the boat. It ran just fine. Check your prop first. Good luck. Steve
Headwind?
How about added HP when you are fighting headwinds? Does anyone know how to calculate that? It must mean a lot, because my old C36 has 21HP and the new ones are 35HP. tm
How about added HP when you are fighting headwinds? Does anyone know how to calculate that? It must mean a lot, because my old C36 has 21HP and the new ones are 35HP. tm
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