OK, I see the point, but in this situation the acceleration (prop pitch) is more important. ( I think...)
I don't think I need a 9.9hp for a Mac25
- Thread starter patrickfarley
- Start date
Also, the weight of the boat (and the distribution of it) matters, so having a very heavy outboard will negatively affect the handling characteristics.
prop pitch AND diameter are the keys, more than HP.
(like Bigger And Wider tires for a 1/4mile car)
you can change pitch for a price, but are limited on diameter by the Lower unit case
(cavitation plate obstruction).
the merc bigfoot series (25hp and up), put the larger LU on smaller engines. so you can swing a bigger wheel.
edit:
-on the heavier 4 stroke engine... more of an issue when sailing. not so much when motoring..
When you have a choppy sea the engine moves up and down, sometimes the prop is out of the water. -not good when fighting a current. (you move backwards, or are turned as you loose the prop.)
(like Bigger And Wider tires for a 1/4mile car)
you can change pitch for a price, but are limited on diameter by the Lower unit case
(cavitation plate obstruction).
the merc bigfoot series (25hp and up), put the larger LU on smaller engines. so you can swing a bigger wheel.
edit:
-on the heavier 4 stroke engine... more of an issue when sailing. not so much when motoring..
When you have a choppy sea the engine moves up and down, sometimes the prop is out of the water. -not good when fighting a current. (you move backwards, or are turned as you loose the prop.)
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Exactly, you get it, you've been there
. What Bill and I are talking about has nothing to do with speed. It isn't about speed at all it is about being able to quickly maneuver the boat and accelerate maybe just 100 feet or less to avoid an obstacle like a buoy. Walt has even said that he has seen the difference in the low pitch high thrust prop that came on his 9.8 in reverse and it is there also in forward in these situations.
Often the channels are not a straight shot in....
... and.....
.... not very wide. Sometimes you are running with or against the current and then have to turn 90 degrees away from it and then back into it or with it.
About the trucks, they don't have the same torque, one was an 8 cylinder with more cubic inches and the other was a smaller 4. The same with one outboard with a larger prop an one with a smaller one.
Personally I give up. I will be glad to continue this with anyone that has been in situations like Bill and I have been talking about and still thinks a 4-6 HP outboard will give you the same performance as the 8-9 HP in those situations,
Sum
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Yes but the 4 cylinder is turbo charged with Nitro. The V8 has to burn 40 % Ethanol.
Of course there is a difference between a 6 hp and a 10 hp in performance.. If you do a lot of motoring in that particular spot Sumner really likes (I may take that one off my list).. get a 10 hp or better yet, get an X or M with 50 to 75 hp.
If you want to optimize sailing, go for the 6 hp. But if your boat is already very heavy on the transom, the weight reduction of the 6 hp wont matter, might as well just get the 10 hp. The 10 hp is somewhat of a luxury, electric start, plenty of power, at least on the Tohatsu/Nissan the charging system makes a significant contribution to the battery, with the high thrust prop, reverse that you have to be careful about ripping the outboard off the transom with - it really is nice to have.
Of course there is a difference between a 6 hp and a 10 hp in performance.. If you do a lot of motoring in that particular spot Sumner really likes (I may take that one off my list).. get a 10 hp or better yet, get an X or M with 50 to 75 hp.
If you want to optimize sailing, go for the 6 hp. But if your boat is already very heavy on the transom, the weight reduction of the 6 hp wont matter, might as well just get the 10 hp. The 10 hp is somewhat of a luxury, electric start, plenty of power, at least on the Tohatsu/Nissan the charging system makes a significant contribution to the battery, with the high thrust prop, reverse that you have to be careful about ripping the outboard off the transom with - it really is nice to have.
A) you guys said nothing about different props, B) if you want better acceleration, you need a LOWER (not higher) pitch prop. We were discussing motors, not props. Unless I got lost somewhere along the way...Exactly, you get it, you've been there
About the trucks, they don't have the same torque, one was an 8 cylinder with more cubic inches and the other was a smaller 4. The same with one outboard with a larger prop an one with a smaller one.
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Never mind. I'm just going to go out and shovel 12 inches of fresh snow before 3 more inches falls...
You are right and I think we have been saying a lower pitch but a larger diameter and more blades all help
. The prop thing did come up back on the first page I think as it is also relevant as you pointed out,Sum
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I think that a 6hp will do it for me and if I can get the overtime I will be ordering soon.
I had a Venture 21 in Florida and the current did not push it around very much when the keel was up. The boat would draw less than a foot of water. It also had a low profile. The wind would not push the bow around like a sail was attached.
The Mac 25 sits much higher in the water and draws 20" even with the keel up. It is easily pushed by currents from the side even with the keel up. The bow sits out there like an extra sail. When waiting for the drawbridge to go up a wind gust can blow you around and then the current takes you from the side. I have had to go around in a circle to get pointed back the right direction.
It always seems to be a problem in the evening. I have been sailing/fishing all day and am tired from the heat(Florida). In the morning the weather is always beautiful and inviting. When I return the wind is coming from who knows what direction, the thunder bumpers are blazing and the evening traffic is more than the bridge tender wants to stop to let me in early(lots of times they have let me in early), with other boats waiting while I am exhausted. This is where I need a motor that will do it all. I have always planned for motor failure and keep two anchors ready, bow and stern. I figured that if need be I can throw them out and at least not be thrown into the bridge or another boat. Then fix the motor or call for a tow. I will just extend the plan to if the 6hp can't keep me off the bridge and throw the anchors out if need be until the bridge is open.(sometimes it seems like it takes forever for the bridge to open all the way).
If I get in big waves and wind I can run under sails for shore. My main has a double reef and my jib is tiny anyway. Or throw out an anchor and go below and relax until the storm passes. If big weather is forecast you will find my boat in a marina or on a trailer and me in a warm comfy room reading a book.
I had a Venture 21 in Florida and the current did not push it around very much when the keel was up. The boat would draw less than a foot of water. It also had a low profile. The wind would not push the bow around like a sail was attached.
The Mac 25 sits much higher in the water and draws 20" even with the keel up. It is easily pushed by currents from the side even with the keel up. The bow sits out there like an extra sail. When waiting for the drawbridge to go up a wind gust can blow you around and then the current takes you from the side. I have had to go around in a circle to get pointed back the right direction.
It always seems to be a problem in the evening. I have been sailing/fishing all day and am tired from the heat(Florida). In the morning the weather is always beautiful and inviting. When I return the wind is coming from who knows what direction, the thunder bumpers are blazing and the evening traffic is more than the bridge tender wants to stop to let me in early(lots of times they have let me in early), with other boats waiting while I am exhausted. This is where I need a motor that will do it all. I have always planned for motor failure and keep two anchors ready, bow and stern. I figured that if need be I can throw them out and at least not be thrown into the bridge or another boat. Then fix the motor or call for a tow. I will just extend the plan to if the 6hp can't keep me off the bridge and throw the anchors out if need be until the bridge is open.(sometimes it seems like it takes forever for the bridge to open all the way).
If I get in big waves and wind I can run under sails for shore. My main has a double reef and my jib is tiny anyway. Or throw out an anchor and go below and relax until the storm passes. If big weather is forecast you will find my boat in a marina or on a trailer and me in a warm comfy room reading a book.
woops, that area from Punta Gorda S. is definately on the list.. A trip I would like to do is tow a Hobie AI down there, park the boat and use the AI. A windy day with lots of current would likely be a lot of fun on the AI (with the sailboat anchored in a cove). Here is a thread of some kayaking adventure in that area - tons of pictures.
http://www.hobiecat.com/forums/viewtopic.php?f=70&t=7276&start=15
This picture is of a 26D with a 6 hp outboard. Fast boat sailed well, I get smoked by this boat.
http://www.hobiecat.com/forums/viewtopic.php?f=70&t=7276&start=15
This picture is of a 26D with a 6 hp outboard. Fast boat sailed well, I get smoked by this boat.
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walt, might consider the 'wilderness waterway' (but only in winter - dec-april - because of the bugs.)
http://www.nps.gov/ever/upload/Wilderness_Trip_Planner_2009.pdf
http://www.nps.gov/ever/planyourvisit/canoe-and-kayak-trails.htm
you could go outside and sail, or inside and paddle.
-I've thought about this in the mac, but 99miles is a long way for a 2 stroke...
I've done parts from everglades city and flamingo but never the whole thing.... (someday)
http://www.nps.gov/ever/upload/Wilderness_Trip_Planner_2009.pdf
http://www.nps.gov/ever/planyourvisit/canoe-and-kayak-trails.htm
you could go outside and sail, or inside and paddle.
-I've thought about this in the mac, but 99miles is a long way for a 2 stroke...
I've done parts from everglades city and flamingo but never the whole thing.... (someday)
I trailer with my 9.9 on the boat. It never comes off. I wouldn't think of any less power. I have used all of it more than once and was glad I had it. As Sumner states channels are always a treat going in or out. I wouldn't try the Cape Cod Canal, Woods Hole or the Westport River entrance with anything less. That is in slack tide never mind the flood! Sometimes you can't fool around. That sudden wind behind you with the nose to the dock will have you kissing the sea prop. I have the three blade mickey mouse prop.
I've got the 1992 Johnson sail master 6hp that came on my 26d. Its a 2 stroke 2 cyl and does just fine maneuvering off the trailer and to the dock... Now getting back on the trailer... with wake board boats on either side, especially if there is a tail wind, forget about it. I use a rope on the stern cleat and guide it on from the dock
My boat came with a 7.5 Honda 4cycle long shaft which is not exactly light. It pushes my M25 to hull speed. It runs out of power at 7/8 throttle when trying to push her any faster than hull speed in calm conditions. When powering into the wind or current I can still approach hull speed. It sips gas and is quiet if you can afford the cost would recommend.
I don't know about props and all but in my limited experience wind can blow and between wind and waves, this can have as much effect as the current. It's when they all gang up on you, you wish you had the power to get into the shelter.
or coming in or out of slip in a tight marina with a lot of wind..
With Macs on this forum, people chose every thing between 90 hp and electric trolling motors with less than 1 hp. Just depends on what tradeoffs you consider important.. no choice is the wrong one. My own opinion - being able to rotate the outboard and keeping the prop in the water are more important than a few extra hp.
It was mentioned in this thread about conventional swept back props cavitating when "gunned" in the forward direction. Ive now had four different outboards that have had the conventional swept back blades and have never experienced this myself.. Ive heard of this before so spent time looking for it.. all Ive felt was thrust when gunned forward. You can see bubbles in the thrust exiting the prop - but that is just the exhaust.
The picture below shows the high thrust prop and the "regular" prop for the Tohatsu/ Nissan 9.8. The high thrust has a larger hub that allows the exhaust to exit through the hub when in reverse. On the conventional prop with the smaller hub, the exhaust has to go over the blades in reverse - not good if your trying to move water. These are the two props I used over a one month period, the four blade prop is a huge amount better in reverse.
But in forward, that three blade prop just delivers thrust when gunned. Its also likely more efficient for long forward runs with the smaller hub and blades optimized for forward motoring.
Both props work well, just optimized for different conditions..
With Macs on this forum, people chose every thing between 90 hp and electric trolling motors with less than 1 hp. Just depends on what tradeoffs you consider important.. no choice is the wrong one. My own opinion - being able to rotate the outboard and keeping the prop in the water are more important than a few extra hp.
It was mentioned in this thread about conventional swept back props cavitating when "gunned" in the forward direction. Ive now had four different outboards that have had the conventional swept back blades and have never experienced this myself.. Ive heard of this before so spent time looking for it.. all Ive felt was thrust when gunned forward. You can see bubbles in the thrust exiting the prop - but that is just the exhaust.
The picture below shows the high thrust prop and the "regular" prop for the Tohatsu/ Nissan 9.8. The high thrust has a larger hub that allows the exhaust to exit through the hub when in reverse. On the conventional prop with the smaller hub, the exhaust has to go over the blades in reverse - not good if your trying to move water. These are the two props I used over a one month period, the four blade prop is a huge amount better in reverse.
But in forward, that three blade prop just delivers thrust when gunned. Its also likely more efficient for long forward runs with the smaller hub and blades optimized for forward motoring.
Both props work well, just optimized for different conditions..
In the 60s hp was rated differently I think , a little on the optimistic side so a new 6 hp motor might have close to the same power as an old 9 hp motor. Your motor has probably lost some power over the decades too from wear and compression loss. The 4 stroke will also give you more torque over a 2 stroke which helps push these larger hulls.
you can see cavitation on a prop, by blisters, or pock marks on the back side of a prop towards the trailing edge (away from the hub). (side of prop facing the boat).
normally it takes many many hours for this to show up... but that's a symptom.
I've spun the hub on my very old 2 stroke 9.9 evenrude (kicker), when limping back into Ft lauderdale, when my skiff's 200 merc water pump failed.
I was still able to go around 2mph with the spun prop... (a lot like a slipping clutch).
-not all small props have a hub... but if you don't then the shaft or lower unit take the shock... when you hit something hard.
Walt, what does the other side of those props look like? solid or rubber hub?
normally it takes many many hours for this to show up... but that's a symptom.
I've spun the hub on my very old 2 stroke 9.9 evenrude (kicker), when limping back into Ft lauderdale, when my skiff's 200 merc water pump failed.
I was still able to go around 2mph with the spun prop... (a lot like a slipping clutch).
-not all small props have a hub... but if you don't then the shaft or lower unit take the shock... when you hit something hard.
Walt, what does the other side of those props look like? solid or rubber hub?
Im not sure (boat is over 800 miles away) but I dont think there is any rubber.. Ill have to check for the pitting next time I see the boat (which might be a couple weeks from now).
Some more pictures of the high thrust prop. This one is 5 pitch, the one that Sumner likes is 7 pitch and probably a better choice than this one I have.
Some more pictures of the high thrust prop. This one is 5 pitch, the one that Sumner likes is 7 pitch and probably a better choice than this one I have.
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Speaking of high pitch - which is better to prevent the prop walk? I added the prop guard (just like the one on the pic), but sometimes I have to raise my keel to leave the dock, and the prop walk is so bad it turns the bow at least 45 degs before I get enough speed to go straight...
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