School me on Hydrofoils

Re-reading your post. What kind of pod do you have? Does the bottom of the hull extend through the pod, or is the pod stepped? On a stepped pod the engines need to be mounted substantially higher than on a hull extension pod. Not necessarily a poorly designed pod - hopefully just poorly mounted engines.

In my experience, when you buy something it will generally 'work' - but if you want it dialed in (boats, cars, gear) - that's up to the end user.
 
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I have a 1998 17' Whaler outrage ii, merc optimax 15O ProXs, no trim tabs. Was having too much bow lift- trim tabs would 100% have worked to fix it but wanted to try the less expensive option since everything else was working so well besides that little bit extra lift. Tried out the no drilling needed SE 300 and it worked great for getting the nose down. No holes, no discernable drag and that nose comes down nicely now with the extra lift in the stern. If you don't have the budget to do tabs I think it's worth a try...then in the future, if you feel tabs could help more, go for it. Cheers
 
Max123 said:
Just to throw this out there - how confident are you in your outboard mounting height?

I've been down this road on two vastly different boats. First boat I owned was a little Lifetimer with a 40hp Suzuki. The first ride was a huge diasappointment - bow was way up in the air, wouldn't plane at low speed, lots of spray off the motor - literally felt like I was dragging something through the water. Let me tell you - I was bummed, having just spend $25k on a custom built boat, and the builder is a ferry ride away. Anyway, It took it to a local shop - first thing they did was suggest the hydrofoil. Totally wrong move. It didn't solve anything - and created even more drag.

Then I started reading about how to mount an outboard correctly...

Long story short, outboard went up 2 holes (one hole at a time - lifted it myself using the trailer jack method), and added 2" of pitch to the prop. Boat flattened out beautifully, planed easier and at a lower speed, easily gained 5 mph, better fuel economy, better handling, etc, etc. Totally transformed the boat from a big old pig, to the nimble/delightful little boat I wanted. I fixed this by reading and doing the work - the shops were no help and just wanted to sell me stuff rather than put in the time. Shops feel like you want 'things' when what you really want is expertise. The only thing I was unhappy with was the fact that I'd caved by adding the hydrofoil and had drilled up my new Suzuki. The hydrofoil actually did have some benefits - the Lifetimer was a small boat and the foil actually stabilizes it quite a bit at speed - but that's not really going to happen on a big boat.

Fast forward to my second boat. 20ft Jasper centre console with an XL/25" 135 Evinrude. Boat already had 4 years and 150hrs under its belt, so you would think that the setup was dialed in. Absolutely was not dialed in - porpoised all over the place, zero ability to trim the engine at speed. This time I knew what to do: in the end the engine went up 3 holes to the very top mounting point. I still have the same prop on it, but could easily go up 1-2" pitch. Totally flattened out the porpoising - better fuel economy, vastly improved handling. Thankfully never added the hydrofoil. Did everything myself - lifted the big Evinrude using the trailer jack method.

I say this with all respect: boat building is not the same as boat commissioning - two separate skills. Most outboards are mounted too low because its the conservative choice and lots of people won't know any better. You only really know a poorly rigged boat if you've experienced a totally dialed in boat. An outboard needs to be sea trialed with the boat loaded up the way you want it. First you adjust the engine mounting (one hole at a time). Only after the engine is mounted correctly can you proceed to step 2: experimenting with prop pitch / style. Playing with props before dialling in the mounting height is a great way to waste your money. Once you've done all of that - move some weight around. Only after that, and the boat is totally dialed should you start playing with tabs and foils. Tabs/foils just hide an underlying problem and kill efficiency.

Twin 250s...I suspect its beyond you to lift it in your driveway. What you can do to help out the shop (and prove that you have a problem): Take the boat out for a fast cruise on flat water with a buddy. Get them to hold the helm steady at speed, say 25-30mph (doesn't need to be flat out - just a comfortable fast cruise) with the motor trimmed as best you can. Go to the transom and take a video of the outboards so that you can see the side / rear - you need a clear shot of how water passes around the lower units. If the anti-cavitation plate isn't skimming the surface of the water - bam that's your problem, full stop. You cannot assess how a boat handles/performs when the outboards aren't mounted correctly. Don't start drilling holes for those foils until you get it mounted right. Once you have the video, you can show it to the mechanic. This can help them when they are assessing. Ideally you only want to lift the engines once - but be prepared to do it two time to get it properly dialed in.
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Thanks for the well thought out
reply.
This is a great read to live on in the sfbc forum for folks down the road.

Yeah, mounting hight is fine. I'm kinda surprised as the shop that installed the motors blew it on several fronts but mounting hight is alright. Might be able to get away with one more hole up.

It is not the right pod for the hull. It's a pod, not an extension. It should have an extension like the Whaler Drive that came from factory. Thatw what it wants but a fool will be much less expensive if it helps significantly.

you male very valid points on weight distribution. I'll toss 300lbs in the bow and see how it goes with that adjustment.

Bigger tabs wouldn't hurt either.

I'm going to swap the props as pitch will be close on the eco enertia I have on the other rig. I'll see how that goes and play with weight and foils from there.
 
Lots of good info here,the only thing I would add is wedges ,I made some fiberglass wedges to my Grady to get the bow down.You can buy aluminum ones .Mine were 5/8: at the top to nothing at the bottom the length of the mounting bracket,and worked great.I'm thinking of doing the same to my Seasport to help with porpoising.Pretty cheap fix.
 
No problem. Here's one thing that people seem to forget about stepped pod design (vs hull extension). Keep the image of a teeter-totter in your mind.

When a conventional boat with continuous hull is planing, only the back 1/2 of the hull is in the water. The front half of the boat that is out of the water is a cantilever - it is this effect that causes the bow to come down when you come up to speed. In a well designed boat, this effect is basically cancelling out the weight of the engines at the stern.

Conversely, when you have a stepped pod, your are creating a much more complicated balancing act. You still have the bow cantilevered off the front, but now you also have a cantilevered weight off the back, because the engines are no longer directly supported by the water. Basically its a asymetrical teeter-totter similar to the diagram below: Adding a bit of weight to the front is going to help offset the effect of the heavy engines cantilevered off the back. Play around with it a bit and see what you get - but this arrangement is always going to be more sensitive to weight balance.


1726072947119.png
 
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PS, on the back of the pod what is the transom angle for the engine mounts? Standard transom angle is in the range of 14 degrees. The angle of the engine mounts should be the same as the factory whaler transom. If the pod was designed with less transom angle, then you may benefit from the transom wedges. If there is no transom angle, your motor won't be trimmed correctly and the bow will stay up in the air.

A side profile photo of the boat out of the water with the engines fully down would provide a lot of information.
 
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seabeyond said:
Thanks for the well thought out
reply.
This is a great read to live on in the sfbc forum for folks down the road.

Yeah, mounting hight is fine. I'm kinda surprised as the shop that installed the motors blew it on several fronts but mounting hight is alright. Might be able to get away with one more hole up.

It is not the right pod for the hull. It's a pod, not an extension. It should have an extension like the Whaler Drive that came from factory. Thatw what it wants but a fool will be much less expensive if it helps significantly.

you male very valid points on weight distribution. I'll toss 300lbs in the bow and see how it goes with that adjustment.

Bigger tabs wouldn't hurt either.

I'm going to swap the props as pitch will be close on the eco enertia I have on the other rig. I'll see how that goes and play with weight and foils from there.
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I would strongly echo advice offered by others who have installed a pod and not an actual hull extension. I have experience with both (first vessel was a pod, second was hull extension) and the only way I could correct the problems you mention on my other vessel with a pod was to install a hydrofoil. That hydrofoil was a simple and cheap fix, it corrected the issues and also gave me more trim adjustment control. On my current Grady, I installed a full hull extension and have not experienced any of the stability issues associated with a pod.

Would not recommend adding weight forward for 2 reasons. First it will degrade performance of the vessel propulsion - think power to weight. Second, the real issue is a pod creates an imbalance by placing the engine out past the transom with no way to support that - it creates the imbalance and poor trim performance because the water flowing from the transom and hull back towards the pod creates a void and disrupted water flow leading to less stable supporting water surface effect. The hydofoil option does help provide mechanical lift to support the weight of the engine while under forward power/movement. This isn't a perfect solution, but it is effective and cheaper than correcting the pod.
 
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Have you guys with a hull extension pod gone with an extra long leg to keep your powerhead well above waterline? 25" or 30"?
 
I can't recall off hand the length of my leg, left that for the experts at Suzuki to match my engine to the hull extension. Sorry.
 
Rayvon said:
Have you guys with a hull extension pod gone with an extra long leg to keep your powerhead well above waterline? 25" or 30"?
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yes 30 inch and sits about 8 inches above water line
 
Rayvon said:
Have you guys with a hull extension pod gone with an extra long leg to keep your powerhead well above waterline? 25" or 30"?
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25 on mine, but every boat is different. Wolfs boat you need a 30 because it is 26 feet and super deep hull. Its not comparable to smaller boat. 25 is what the Suzuki motor guys recommended.
 
SpringVelocity said:
25 on mine, but every boat is different. Wolfs boat you need a 30 because it is 26 feet and super deep hull. Its not comparable to smaller boat. 25 is what the Suzuki motor guys recommended.
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A 25 can and will work the "other " hourston has a 25 i went with the 30 so i had more motor out of water and a higher pod
 
Update:

Installed the se400 foils and took it for a test run in ideal conditions last weekend.

What a game changer for this boat. It's like an entirely different machine, in calm water anyways. Rides much flater, gets on step considerably quicker, and holds plane down to 14mph. 20% increase in mpg through the 16-23 mph range and still reaches 50 at wot. These did everything I had hoped for thus far.

I'm curious how it preforms under normal load (It was only me on board with 100 gal in the tank) and in typical conditions. I'll have to get it out again before I pull it for the winter.

A note that the no drill option really doesn't work on the 8" wide cav plate of the V8 merc. It only species a Honda and the 350 yam as needing modifications but I suspect the literature hasn't been updated since prior to the merc 2018 v8 introduction. Instal was a pain for the no drill option. I doubt it'll stay on there long term so I'll drill them on there now that I see they work. Not a big fan of drilling holes in these cav plates but it is what it is.

I will try a prop swap to the eco enertia 18 as I am suspicious this hull can get better mid range economy than it currently does. Whether it's worth the 3k in props and hub kit is debatable. I guess I'll get a better idea of the potential pay off when I swap the props and give it a test run.

Thanks for the feedback on the thread fellas.
 
Well that's a good performance increase. I imagine the MPG improvement is mostly due to getting the boat planing more level rather than plowing through the water.

I'm also curious how the Enertia ECOs help the boat.
 
seabeyond said:
Update:

Installed the se400 foils and took it for a test run in ideal conditions last weekend.

What a game changer for this boat. It's like an entirely different machine, in calm water anyways. Rides much flater, gets on step considerably quicker, and holds plane down to 14mph. 20% increase in mpg through the 16-23 mph range and still reaches 50 at wot. These did everything I had hoped for thus far.

I'm curious how it preforms under normal load (It was only me on board with 100 gal in the tank) and in typical conditions. I'll have to get it out again before I pull it for the winter.

A note that the no drill option really doesn't work on the 8" wide cav plate of the V8 merc. It only species a Honda and the 350 yam as needing modifications but I suspect the literature hasn't been updated since prior to the merc 2018 v8 introduction. Instal was a pain for the no drill option. I doubt it'll stay on there long term so I'll drill them on there now that I see they work. Not a big fan of drilling holes in these cav plates but it is what it is.

I will try a prop swap to the eco enertia 18 as I am suspicious this hull can get better mid range economy than it currently does. Whether it's worth the 3k in props and hub kit is debatable. I guess I'll get a better idea of the potential pay off when I swap the props and give it a test run.

Thanks for the feedback on the thread fellas.
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This post caught my eye, despite my boat getting on plane quickly and not having bow-high trim issues. What piqued my interest was @seabeyond can now stay on plane all the way down to 14 kn. My hull drops off plane around 16-17 kn and plows along bow up, thirstiest rpm range other than WOT. My transom has this weird layout and I don't see any room for trim tabs, but a hydrofoil might be worth trying. Not a big cash commitment, and easy to remove if not helping.
 
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