Hydro Foil

[Davis 103]

I run a 2011 4 stroke 6 HP Tohatsu on a 10' 3" Pelican 103.
would a hydro foil / Doel Fin or a simiular product help the preformance on a motor this small?
I have changed from a factory 8 pitch to a 7 pitch and incresed my "hole shot" and lowered the RPM's it takes to keep the boat on plane, however I have to place the trolling motor battery, 3 gal fuel tank and all other gear as close to the bow as possabile. I would like to place the fuel tank in the rear and the battery in the compartmnet that is pre wired for this purpose.
My basic question is : do products like these work on a small motor and boat ? trim tabs are out of the question as this is a plastic boat.

I look forward to your comments and knoweldge.

Thanks



"use it daily or watch it rust"

 

[Sea Rider]

Re: Hydro Foil

Will depend on how loaded is your boat/engine combo for that given engine, if light loaded will plane faster with hidro foils, if heavy, whatever you add to tail, won't plane at all. Distribute weight forward to have a well ballanced boat.

Happy Boating

 

[JB]

Re: Hydro Foil

Lengthening that short hull bottom should definitely help with getting on plane and staying there at relatively low speeds with such low power, Davis.

I would use a SE Sport Jr. or other one piece hydrofoil rather than a Doel Fin.

Good luck.

 

[Davis 103]

Re: Hydro Foil

I just got back from the lake, I moved the fuel tank to the front and changed the trim pin to the 3rd setting. boat planes quickly and stays on plane at 4,300 RPM. great handling and preformance with this one change. I dont think I need a hydo foil since it planes quickly now. however would there be any benfit to a small "jack plate" to help move the motor futher back?

Thanks for the answers, as Sea Rider said "a balanced boat" makes all the differnce especialy on such a small boat.
Thanks again for the advice .

 

[Sea Rider]

Re: Hydro Foil

Davis 103, if third hole trim position and moving weight forward gives you a parallel boat to surface while at wot, you are at the correct hole. A matter of moving weight forward and playing with trim hole to achieve this position. Why would you need to move engine furhter back ?

Happy Boating

 

[Davis 103]

Re: Hydro Foil

The reason I asked is because I do get spray on both sides of the transom, its only a little water but it does get into the boat at WOT. it's not that big of a issue could manfacture 2 small plates that sit atop the transom to keep the water spray from coming in.
As you said I think I found teh balance that this boat needed, thanks again for the advice.

 

[Sea Rider]

Re: Hydro Foil

Is water spray entering sib at tube's sideways as described and through middle engine sides too at same time at wot ? What's the height of your transom top to middle lower keel in centimeters 38,39,40 ?

Happy Boating

 

[Davis 103]

Re: Hydro Foil

when I installed the motor i made sure that the ventlation plate was in line with the bottom of the hull, I will have to mesure to get the excat centimeters.
the water is splashing over at both sides of the corners of the transom.

 

[Sea Rider]

Re: Hydro Foil

"I made sure that the ventlation plate was in line with the bottom of the hull", this principle is not cast in stone, not always works as expected, the final adjustment is made under trial & error, sometimes you'll need to raise engine a bit to eliminate unwanted splash problems, will be interesting to know your sib's middle transom height. Tohatsu's are prone to water splashing issues at back transom if they don't seat at a correct height to match their lower unit.

Happy Boating

 

[Davis 103]

Re: Hydro Foil

I have placed a plastic shim about 1/4" ontop of the transom, I will se how this works on friday.
thanks for the tips and advice.
even with this issue, i would recomend the Tohatsu engine, this little one cylinder runs great with litte vibration and preforms very well,

 

[Sea Rider]

Re: Hydro Foil

Let us know if placing a shim bettered the splash issue...

Happy Boating

 

[Davis 103]

Re: Hydro Foil

the plastic shim took care of most of the "water splash" over the transom, all I did was place a hard plastic shim the same size and the top of the transom which allowed me to not change the clamp placement of the motor by much, this has taken care of the problem.
if anyone is having a simulair issue i would be happy to send some pictures of the install.

David 103

 

[Sea Rider]

Re: Hydro Foil

Now that you have raised a bit the engine on trasnsom, check when at plane if water flow passes over or under small upper plate, if passing slightly over, still will produce small water splash, will need to raise engine enough untill flow passes slightly under small plate, will achieve best top speed with normal water drag against tail. Is a Pelican 103 a inflatable ?

Happy Boating

 

[Davis 103]

Re: Hydro Foil

The water flow is slightly above the plate as shown in your pictures, my concern is that if I raise the motor more with shims ontop of the transom I will be raising the bracket clamps to high on the transom and loose some structurial intergerity of the transom with this being a "plastic boat" that is why I was thing a small jack plate mayhelp.
what are your thoughts?
this is a Pelican 103, 10,3". as it is it sems to run well but I would like to get it to close to perfectly balanced as possabile.
thanks for your insight,

Davis 103

 

[Sea Rider]

Re: Hydro Foil

As don't know this boat, is it possible to add a slight thicker shim and raise both engine plates, if this model has them to match upper shim border ? When I say that Tohatsu is a natural water splasher if not perfectly transom seated it's because if you look closer to first pic, will see that lower plate has a triangle shape that cuts water flow at plane, on upper plate, water flow simply smashes against non triangular portion producing water splashes, the lower the engine sits the worst will splash increasing tail drag and lessening boat's top speed.

That's why Tohatsu's works best on transoms having at least 40 cm height with respect to keel. If nothing can be done on that Pelican, could add 90? splash guards made from pvc fabrics glued on top transom & tubes corners.

Happy Boating

 

[Davis 103]

Re: Hydro Foil

this makes sense, the "water splash" is much worse on the right side looking at the boat from the back. i am installing another shim this weekend, i believe this should take care of the issue given the info provided.
again, thanks for the informatiom.

 

[Sea Rider]

Re: Hydro Foil

If you are a heavy champ sitting on right side will have more water splash to that side, as a test, sit in middle deck and wot, see if splashes are even to both sides, raising a bit the transom's shim will smooth out the ride.

Happy Boating

 

[Davis 103]

Re: Hydro Foil

the seeting in the boat is directly in the center, I have moved the battery for the trolling motor to the center as well, the "splash" is much less however it still is more on the right side (looking at the boat from the front) it is performing well the only issue that I have now is that it will only get to 5600 RPM at WOT without anything in the boat but me, 3 gallon tank and motor, the boat only weighs 155 lb's. it planes well and maitains the speed well. I am very please with this little motor I have had no issues with it, i would just like to get the most preformance that I can, however i am happy with the current preformance.

I do apoligize that it took me so long to get back to you, I had a very bad wreck a few weeks ago, i totaled my 2011 Dodge with less than 20k miles. but thank God I only got a exploded spinal disc and a few cracked verbrate. it could have been worse.

Thanks for your help.

 

[pvanv]

Re: Hydro Foil

The WOT RPM rating for that motor is 5,000 - 6,000, so you are right in the range at 5600.