Fin for Yamaha F 50

twogone

Active Member
I have a 16 ft Harbor Craft and was have just put a new motor on it. The motor I selected, based on advice from friends, is a 4 stroke Yamaha F 50. The previous motor was a 4 stroke (American, made by Suzuki) Evenrude 40 HP. Except for trolling, it was a peach, quiet & ran all day on a tank but it has water in the crank case and is effectively dead. Even though the Yanaha has an extra 10 HP, it struggles (much more that the 40 HP Ev) to get the boat on plane. It has been suggested to me the Evenrude was over prop'd so had more ''poop'' out of the hole and that also contributed to the difficulty I had getting it to slow down for trolling. It DID have a bigger prop that the Yamaha has. I am very reluctant to change the prop on the Yamaha because it trolls beautifully; infinitely better than the old Ev. I am told a fin can be attached to the Yamaha that will lift the stern and put the boat on plane much quicker and once on plane, a small adjustment to motor trim will level the boat and improve fuel efficiency. Can someone recommend a fin for the Yamaha F 50. I have looked at the Permatrim hydrofoil fins, they are aluminum and look pretty nice (also available in ''made to fit'' for Yamaha but they are quite pricey compared to the others. Any suggestions, recommendations or comments would be appreciated. Many thanks! Twogone Cassidy BC
 
I had an ouboard fin on my boat and it would come on plane faster with then without, however it did not cure the porposing that I had. I also found that the steering was (tiller) odd and had a tendency to yaw at times. The cure was to install a couple of fallers' wedges between the engine mounting bracket and the transom to increase the "under angle". This may or may not be related to your problem. Another thing to consider is your engine mounting height, in particular how far above or below the bottom of your hull the cavitation plate sits. But to answer your question there is no doubt that you will come on plane faster with a fin. What is your RPM at full throttle and wound right out? If you are not achieving between 5500 and 6000 rpm then you need a smaller prop. Anything above 6000 rpm is too small a prop.
 
I had a 2006 Harbercraft with a 60 hp Mercury 4 Stroke. I thought it was underpowered with this motor. It would do 30 mph at 6,000 rpm and alright out of the hole. On one trip, I had my nephew and a buddy (100-120 lbs each) and a cooler of halibut.... I could not get the boat up on plane.

I would only carry 1/2 to 3/4 of a tank of gas and a spare can up in the bow just to get the weight forward. I'm not sure one of those fins will do much. If you want a better hole shot, go down a pitch on the prop.
 
My boat is underpowered and used to porpoise a bit if I took my cannonballs out of the bow locker. These helped a lot with getting up on plane quicker and staying up running in heavy slop at 13-14 knots. 17' whaler tiller Merc 50hp 4s with kicker and a heavy guy in the driver seat.
I had to dremel the plastic a bit. I didn't mind drilling holes in an older motor but would look for a no drill version if my motor was new.
https://www.amazon.ca/Attwood-Outbo...ocphy=1001909&hvtargid=pla-567868750502&psc=1
 
I put an SE Sport Hydrofoil on my previous two boats. One was on a 115Hp Honda and the other was on a 150Hp Yamaha. On both of my applications the Foil worked as advertised and was noticeably better at lower speeds in a following sea. I did have to drill holes but I just used a good sealant like 5200 and never have any issues with either boat.
 

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I had an ouboard fin on my boat and it would come on plane faster with then without, however it did not cure the porposing that I had. I also found that the steering was (tiller) odd and had a tendency to yaw at times. The cure was to install a couple of fallers' wedges between the engine mounting bracket and the transom to increase the "under angle". This may or may not be related to your problem. Another thing to consider is your engine mounting height, in particular how far above or below the bottom of your hull the cavitation plate sits. But to answer your question there is no doubt that you will come on plane faster with a fin. What is your RPM at full throttle and wound right out? If you are not achieving between 5500 and 6000 rpm then you need a smaller prop. Anything above 6000 rpm is too small a prop.
Thank you for your reply. To answer your questions, there does not seem to be a porposing problem when we finally get up on the plane; I don''t know anything about the motor angle or mounted height but it was installed (quite expensively) by the Yamaha dealer in Port Alberni and one must assume they know what they are doing. (other than $$$$ their service was EXCELLENT!!); The motor is brand new and my son and I fished it for a week at Nootka. As per instructions, we avoided high revs for the first 20 hours but after that we did run it up a few times and I believe the revs went very slightly over 6000. To be fair to the motor, it added 15 mph over the old Evenrude. I am reluctant to add prop because the boat now trolls beautifully. I would just like to have it get up on the plane a bit quicker. My son had to go up to the bow to make it plane which is somewhat disappointing because I paid the extra$$$ for 10 more hp to avoid just that. I'm 300 lbs but sit in the middle. There is nothing at the stern other than motor, fuel, 2 batteries, 2 downriggers and (hopefully) a tote with some fish).
 
I had a 2006 Harbercraft with a 60 hp Mercury 4 Stroke. I thought it was underpowered with this motor. It would do 30 mph at 6,000 rpm and alright out of the hole. On one trip, I had my nephew and a buddy (100-120 lbs each) and a cooler of halibut.... I could not get the boat up on plane.

I would only carry 1/2 to 3/4 of a tank of gas and a spare can up in the bow just to get the weight forward. I'm not sure one of those fins will do much. If you want a better hole shot, go down a pitch on the prop.
Thank you for your reply. Perhaps I should have added 20 hp to the old Evenrude but that motor (40hp) did such a good job I just assumed an additional 10hp would do the trick. Also, the ól pension (or the local minister of Finance) may not have allowed the extra 20 hp. I am not obsessed with speed and the boat is primarily used for fishing so being able to control bottom end speed it important to me. I also paid extra $$ for the electronic rpm controls which allow me to add or subtract 50 rpm increments to the motor right on the dashboard. Pretty tough to do that with cable controls.
 
My boat is underpowered and used to porpoise a bit if I took my cannonballs out of the bow locker. These helped a lot with getting up on plane quicker and staying up running in heavy slop at 13-14 knots. 17' whaler tiller Merc 50hp 4s with kicker and a heavy guy in the driver seat.
I had to dremel the plastic a bit. I didn't mind drilling holes in an older motor but would look for a no drill version if my motor was new.
https://www.amazon.ca/Attwood-Outbo...ocphy=1001909&hvtargid=pla-567868750502&psc=1
It IS a brand new motor. I have not seen ''no drill'' versions but will look for them. Fortunately, my neighbour is a very accomplished mechanic with quite a bit of marine experience so whatever I choose, he will probably install for me. Thanks for your suggestions.
 
I put an SE Sport Hydrofoil on my previous two boats. One was on a 115Hp Honda and the other was on a 150Hp Yamaha. On both of my applications the Foil worked as advertised and was noticeably better at lower speeds in a following sea. I did have to drill holes but I just used a good sealant like 5200 and never have any issues with either boat.
Thanks for your reply. Foil #1 looks like it is perfect for that motor. I wonder why the manufacturers of these motors don't offer them (built in) as an option.
Being a small boat (16 ft) with a quite elderly Capt./operator I tend to avoid rough water (OK, I'm a chicken S%$t).
 
I searched iboats and others and can not find a definite answer. A prop shop should know. When I changed, I did not notice a difference. Getting on plane quickly however is 100x better for me
 
Thank you for your reply. To answer your questions, there does not seem to be a porposing problem when we finally get up on the plane; I don''t know anything about the motor angle or mounted height but it was installed (quite expensively) by the Yamaha dealer in Port Alberni and one must assume they know what they are doing. (other than $$$$ their service was EXCELLENT!!); The motor is brand new and my son and I fished it for a week at Nootka. As per instructions, we avoided high revs for the first 20 hours but after that we did run it up a few times and I believe the revs went very slightly over 6000. To be fair to the motor, it added 15 mph over the old Evenrude. I am reluctant to add prop because the boat now trolls beautifully. I would just like to have it get up on the plane a bit quicker. My son had to go up to the bow to make it plane which is somewhat disappointing because I paid the extra$$$ for 10 more hp to avoid just that. I'm 300 lbs but sit in the middle. There is nothing at the stern other than motor, fuel, 2 batteries, 2 downriggers and (hopefully) a tote with some fish).

I am pleased to learn that your boat does not porpoise. If your rpm goes above 6000 revs at full throttle, but it trolls like you want it to, I would stick with what you have for a prop, at least for the time being, keeping in mind that 6000 rpm should be the very extreme limit of your engine and should be considered a red line. If you do not wish to purchase a new prop go back to your Yamaha dealer and ask for a slightly higher pitch propeller to try out at no cost to you. My dealer here in Campbell River allowed me to try out three different props before buying one. That your son moving to the bow helps with the planing tells me that a fin would indeed help you get up on plane, just continue to monitor your top rpm.
 
There's a huge variety of props available for the F50. For example you might have a 10 3/8 x 13 when what you actually need is an 11 5/8 x 11. Most dealerships will help find the right one.
 
I am pleased to learn that your boat does not porpoise. If your rpm goes above 6000 revs at full throttle, but it trolls like you want it to, I would stick with what you have for a prop, at least for the time being, keeping in mind that 6000 rpm should be the very extreme limit of your engine and should be considered a red line. If you do not wish to purchase a new prop go back to your Yamaha dealer and ask for a slightly higher pitch propeller to try out at no cost to you. My dealer here in Campbell River allowed me to try out three different props before buying one. That your son moving to the bow helps with the planing tells me that a fin would indeed help you get up on plane, just continue to monitor your top rpm.
Many thanks for sharing your wisdom & experience Gungadin! I will do some thinking over the winter regarding a slightly more aggressive prop vs a fin of some sort. If the fin works and the cost is reasonable that is probably the way I will go. There are some really nice looking ones that are made specifically for the Yamaha F 40/50/60. Changing the prop would not be completely free even if the Yamaha dealer did the job for no charge because I would probably have to tow the boat over to Alberni & back so time and fuel would be involved (unless I was going to Alberni for something else). Thanks again; Twogone
 
There's a huge variety of props available for the F50. For example you might have a 10 3/8 x 13 when what you actually need is an 11 5/8 x 11. Most dealerships will help find the right one.
Hi Mcfuzza; Thanks for your reply & suggestion. When I took the boat & motor to the dealer for the 20 hour service, I mentioned the fact the new motor, at 10 more hp, did not put the boat on plane (with the same load) nearly as quickly as the old Evenrude. They said they could change the prop but recommended against it because I was so pleased with how the boat trolled. Prop or fin?? I have to do something because I hope to take my little grandson out next spring and he is not heavy enough to get the bow down like my son can (by going up front). Thanks again! Twogone
 
I went through all this with a 20' Thunderjet with a Suzuki DF115. You have to follow a sequence to get the right propping. (underpowered boat)

First and foremost you have to have the engine at the proper height. When running at plane you have to have the cavitation plate at, or, just above the water level. This is very important. Too deep = too much drag and hard to get out of the hole. Too high and it will blow out on turns. Most motors are too deep when rigged as they go the safe route instead of the most efficient route.

I then got hold of Ken @ Propgods in Florida. He had me give him a set of speed readings at a bunch of RPM levels. From this he diagnosed where I should go. My boat was over propped and could not reach full recommended RPM (not good). You don't seem to have that problem as you can get up to RPM well.

I ended up going to a 4blade stainless prop that provided much more stern lift and it completely changed the characteristics of the boat. It comes out of the hole so much better and can stay on step at a much lower speed. Also with a light load, I am just bumping the rev limiter.

Different props do different things on a boat and Ken is a master of dialing your boat in.

The right prop should not change your trolling characteristics as you should not be messing with the pitch of the prop much because your RPMs are good. Stainless props usually run a little bit different pitch than aluminum.

Lots of people try a few props until they find one that gives them acceptable performance but I was happy that I contacted someone who knows his stuff and I feel that my boat is giving me the best performance that it can with my limited power.

Jack
 
I went through all this with a 20' Thunderjet with a Suzuki DF115. You have to follow a sequence to get the right propping. (underpowered boat)

First and foremost you have to have the engine at the proper height. When running at plane you have to have the cavitation plate at, or, just above the water level. This is very important. Too deep = too much drag and hard to get out of the hole. Too high and it will blow out on turns. Most motors are too deep when rigged as they go the safe route instead of the most efficient route.

I then got hold of Ken @ Propgods in Florida. He had me give him a set of speed readings at a bunch of RPM levels. From this he diagnosed where I should go. My boat was over propped and could not reach full recommended RPM (not good). You don't seem to have that problem as you can get up to RPM well.

I ended up going to a 4blade stainless prop that provided much more stern lift and it completely changed the characteristics of the boat. It comes out of the hole so much better and can stay on step at a much lower speed. Also with a light load, I am just bumping the rev limiter.

Different props do different things on a boat and Ken is a master of dialing your boat in.

The right prop should not change your trolling characteristics as you should not be messing with the pitch of the prop much because your RPMs are good. Stainless props usually run a little bit different pitch than aluminum.

Lots of people try a few props until they find one that gives them acceptable performance but I was happy that I contacted someone who knows his stuff and I feel that my boat is giving me the best performance that it can with my limited power.

Jack
Thanks Jack. I will certainly keep that in mind as I bumble my way towards next season. Cheers; Twogone
 
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