School a newbie on outboard maintenance

[SIBRider]

Why would you need one. Our boats are extremly easy to get on a plane otherwise it's just more stuff to drag through water

[F470]

Better fuel economy and lower minimum planing speed from what I hear.

[SIBRider]

I think they come together. Sort of. Lower planing speed means higher fuel economy for boats that have harder time getting on plane needing otherwise more speed consequently fuel. We are in totally different boat especially with comparatively light weight engine. Pun intended. At higher speed it will add drag decreasing speed and efficiency especially without power trim since it may not be positioned perfectly because angle of attack can only be adjusted at discreet interval.

[F470]

I went for a second ride with the motor this weekend. It splashes a good amount at high speeds and some backwash happens over the transom into the boat. Is this standard for a FC-470? I assume a permatrim hydrofoil would reduce this.

I also manage to break off a grease nipple. Are they replaceable? Can I get a generic one or are they specific to make/brand?

Lastly there's a sticker that says my motor has to be bolted to the transom. Is this necessary/required? If so, do I bolt it straight through the transom?

[SIBRider]

How low is anti-cavitation plate in relation to hull/keel. What trim settings are you riding with.

Most likely you have to raise motor considerably depending on shaft length for good performance/economy/reduced splashing. That would most likely mean bolting it to transom. Clamps won't allow it to go high enough. You might be able to do that without building riser if it's short enough. But for example in my case (22" leg) top bolt would basically line up with edge of transom. My motor doesn't have height adjustment holes like larger outboards do.


Hydrofoil will not address this issue at all. Your gear case rides way too low.
Anti-cavitation plate sits way under water at this time. Deflector plate - one above flange that connects gear case to lower leg is likely under water too or to low to offset big bow wave created by low hanging gear case/leg cutting water. Water creeps up transom and leg splashes everywhere. Low riding gear case creates immense drag that slows you down and wastes fuel.

They ask you to bolt it down for safety. Far less likely to loose it. IMHO hydrofoil and clamps only is asking for trouble. Intent is to create lifting force. It it does then I wouldn't trust the clamps necessarily. Let alone hydrofoil would be fixing non-existing problem.

I imagine those are standard nipples. Particularly since they fit standard grease gun. Back stump out. I've sheared them off on couple occasions on my trucks. Japaneses and domestic. Replaced them just fine with what's available in parts store. They cost few pennies.

[jyasaki]

Originally Posted by F470

I went for a second ride with the motor this weekend. It splashes a good amount at high speeds and some backwash happens over the transom into the boat. Is this standard for a FC-470? I assume a permatrim hydrofoil would reduce this.

If it's at speed, probably not. The splashing is likely coming off the leading edge of the LU. That's not an area covered by the foil (the foil does a couple of things, as I understand it: isolates air and prop for less aeration, and redirects upward water flow back down, which is where the lift comes from. It's not acting as a wing, as far as I know.)

Reducing splashing generally means raising the motor on the transom, as long as it doesn't cause aeration (usually in tight turns.) Some people who can't raise the motor have fitted panels to block spray from coming over the transom.

I also manage to break off a grease nipple. Are they replaceable? Can I get a generic one or are they specific to make/brand?

I assume they come in 2 flavors, Imperial and metric, though I have no evidence to back that up. They are simply threaded in in most cases. Should be able to find some at a local auto parts place, and as I recall they're cheap enough that if they don't fit, it won't hurt much.

Lastly there's a sticker that says my motor has to be bolted to the transom. Is this necessary/required? If so, do I bolt it straight through the transom?

Probably not, but make sure any clamp screws are *very* secure. Many people also tether the motor to the boat with a stainless cable just in case the motor decides to jump ship.

If you do decide to bolt it, drill through slightly oversize, epoxy line (or glass, or otherwise seal) the bored holes to seal them up, and use caulk or PU sealant on the nuts and bolts at the inner and outer joins. Transom rot is not an easy fix.

jky

[F470]

Thanks for all the info! I took the motor off yesterday to sand & paint. I will take measurements and report back once it's back on.

[F470]

Here's a photo. I didn't have time to measure but it does appear that the cavity plate is a couple inches too low. What do I do about this? The fuel economy also seems poor.

[SIBRider]

Nice pain job. Is it?
My interim solution is pictured above. Doubt there many other economical options. Economy is naturally not a strongest point of 2 stroke exacerbated greatly by low dragging gear case.

[jyasaki]

That looks like more than "a couple of inches" too low. The pic looks like the splash plate (a couple of inches above the actual anti-ventilation plate) is below the keel line. Puts the LU way too deep, which increases drag by a significant amount, and puts the fat part in the water which explains your splash problem...

jky

[paddlers]

That leg looks far too long for that transom !!

[SIBRider]

Standard "problem" with all F470 they come with 18" transom. Short shaft is too short, long shaft is too long. Go figure. I'm sure there is a good reason for it that doesn't really apply to our civilian use.

[F470]

So I'm going to have to fabricate a transom riser plate? I get the boat back in a couple of weeks so I will report back once I have taken better measurements.

[SIBRider]

Either that or jack plate.

[kiwiboyd]

Originally Posted by SIBRider

Standard "problem" with all F470 they come with 18" transom. Short shaft is too short, long shaft is too long. Go figure. I'm sure there is a good reason for it that doesn't really apply to our civilian use.

These are the following shaft lengths for the current f470's
Z80226 is a 15" transom
Z80224 is a 18" transom
Z80247 is a 20" transom
Aztec F470 is also a 20"
Berry f470's started as 20" and now are 18"

The army buys Z80224's and the Air Force buys Z80247's. the most common is the 18" transom with a 20" shaft motor.

The 15" transom is seldom sold as only Tohatsu make a 50hp 15" outboard, everyone else has 20" shafts.

[F470]

So do most people use a riser plate then in order to accommodate a 20" motor on an 18" transom?

Looks like my transom is about 4.75 - 5" above the cavity plate on my motor. Its about level with the fins above the cavity plate.

I just spent a lot of time and effort rebuilding the transom so I'm not particularly motivated to remove it all and drill holes in the transom in order to be able to use a riser.

Am I better off with a short shaft? Looks like fuel economy took a major hit on my last trip as well.

Originally Posted by kiwiboyd

These are the following shaft lengths for the current f470's Z80226 is a 15" transom Z80224 is a 18" transom Z80247 is a 20" transom Aztec F470 is also a 20" Berry f470's started as 20" and now are 18" The army buys Z80224's and the Air Force buys Z80247's. the most common is the 18" transom with a 20" shaft motor. The 15" transom is seldom sold as only Tohatsu make a 50hp 15" outboard, everyone else has 20" shafts.

[F470]

Where did you purchase your transom riser plate?

Originally Posted by SIBRider

How low is anti-cavitation plate in relation to hull/keel. What trim settings are you riding with.

Most likely you have to raise motor considerably depending on shaft length for good performance/economy/reduced splashing. That would most likely mean bolting it to transom. Clamps won't allow it to go high enough. You might be able to do that without building riser if it's short enough. But for example in my case (22" leg) top bolt would basically line up with edge of transom. My motor doesn't have height adjustment holes like larger outboards do.


Hydrofoil will not address this issue at all. Your gear case rides way too low.
Anti-cavitation plate sits way under water at this time. Deflector plate - one above flange that connects gear case to lower leg is likely under water too or to low to offset big bow wave created by low hanging gear case/leg cutting water. Water creeps up transom and leg splashes everywhere. Low riding gear case creates immense drag that slows you down and wastes fuel.

[F470]

I installed a Permatrim yesterday. I know I need a transom riser as well but I am interested in seeing what difference this makes if any.

Originally Posted by jyasaki

AFAIK, no standard for bolt patterns.

I'd look at the Permatrim line if I had to replace mine (might anyway if I ever get some disposable income.)

They're distributed in the US by Shipyard Island Marina, I think.


jky

[morin1]

Installation of the Permatrim
I'm afraid the bolts are on the wrong side. As soon as you will reach planning speed (when the height of the engine is correct) water flow will be under the anti-cavitation plate. This is why you want the smoothest parts (bolt head instead of the nut) under the anti-cavitation plate.

[F470]

Thanks! I thought about it and I had poor directions that didn't mention screw orientation. Easy enough to change around.