Critique My Suzuki Mounts

[Sharphooks]

So I finally got a chance to take some pictures of my twin DF300 ventilation plates relative to the hull of the boat

I’ve whined in the past about disappointing fuel burn (1.3–1.5 Gph with fuel tanks half full)

What do you guys think of the way they are hung on the transom? The guy who hung them invited me to lift them north a hole but cautioned there might be cavitation on turns

The way they are mounted now—-rock solid prop grip in any water condition, including following seas

Should I just shut up and call it good and eat the crappy fuel burn?

 

[Brando]

are the plates buried when your running?

 

[salmonkiller01]

Check your cavitation plates at speed. Can not tell by the angle of the picture. The diagram is transom mounted higher than hull if bracketed

 

[Sharphooks]

are the plates buried when your running?

I'd say they're just under the surface. FRom the eye-ball measurement I did today, Slmonkiller, the DF300's seem to match your diagram (ventilation plates relative to bottom of boat)

 

[Brando]

I'd say they're just under the surface. FRom the eye-ball measurement I did today, Slmonkiller, the DF300's seem to match your diagram (ventilation plates relative to bottom of boat)

should be ok to go up higher then, how much is trial and error but ideally the cav plate is just out of the water while on plane. How much that will improve fuel economy is also just a guess but getting the correct motor height is a start. You can then start experimenting with props.

 

[Husky]

Just add a jack plate, minimal offset, get it roughly correct then you can tune them as you go. This was my solution to getting it right.

 

[mikep]

I 2nd the jack plates. They work so well. Gets you right in the sweet spot.

 

[wolf]

Looks fine to me ....GAS is the cheapest expense on our boats

 

[Max123]

On both of my boats, the outboards were installed too low, and prop'd too conservatively from the original builder. In both cases, the way the boat felt + fuel burn were significantly improved by lifting the motor. There are general rules of thumb for setting mounting height, but you can't rely on that and no one can really tell for sure based on the photo provided.

You need to get it up and planing at a fast cruising speed (likely around 25mph+, doesn't need to be WOT but the boat needs to fully settle), and loaded the way you want. Then, get someone to hold the wheel and you look over the transom. If you see the anti-cavitation plates cleanly skimming above the surface - then you are good, and there is no benefit to raising the motors (take a video with your phone for future reference). If the anti-cav plates are below the waterline, then you 100% need to raise it up - you are just dragging extra metal through the water, and killing your handling.

 

[ship happens]

You have a side view? Just to get a better idea of the boat and bracket. Looks way to low to me

 

[wolf]

You have a side view? Just to get a better idea of the boat and bracket. Looks way to low to me

Really hard to tell but the best way what ive been shown and taught is a straight edge on bottom of pod and cavitaion plate should be about 3/4 above that. correct? if the boat doesnt cavatate on turns may be right?

 

[ship happens]

Really hard to tell but the best way what ive been shown and taught is a straight edge on bottom of pod and cavitaion plate should be about 3/4 above that. correct? if the boat doesnt cavatate on turns may be right?

Yeah but that's a stepped pod, at least it's what it looks like. I've seen some have to go up as far as 2 inches per foot of setback

 

[seahorse]

I had this same issue on my factory podded Grady 228 Seafarer and my DF250, it was too low and sluggish when it was first mounted. I raised it over 2 inches and now it’s perfect. I seem to remember that the cavitation plate should be 2 - 2 1/2 inches higher than the keel as measured with a straight edge when 30 inches back from the transom on the pod. Raising the outboard also eliminated the V spray from the deeper engine.

 

[Flashman]

On both of my boats, the outboards were installed too low, and prop'd too conservatively from the original builder. In both cases, the way the boat felt + fuel burn were significantly improved by lifting the motor. There are general rules of thumb for setting mounting height, but you can't rely on that and no one can really tell for sure based on the photo provided.

You need to get it up and planing at a fast cruising speed (likely around 25mph+, doesn't need to be WOT but the boat needs to fully settle), and loaded the way you want. Then, get someone to hold the wheel and you look over the transom. If you see the anti-cavitation plates cleanly skimming above the surface - then you are good, and there is no benefit to raising the motors (take a video with your phone for future reference). If the anti-cav plates are below the waterline, then you 100% need to raise it up - you are just dragging extra metal through the water, and killing your handling.

That matches my understanding. You have to look at the engines when on plane, adjust, check again. Compare fuel economy, turning performance, running in rougher conditions and pick where you like them best height wise. Or get Jack plates and be able to tune them for the conditions on the fly.

 

[wolf]

Yeah but that's a stepped pod

Ahhh ok couldnt tell that, was hard enough to see the bottom of the pod..

 

[Max123]

@Flashman - 100%. Rough water performance is something I left out. There are good reasons to mount the engines lower than may be optimum. If you test your setup on glass smooth water you may find that you lose traction in rough conditinos (not always, as you will tend to go slower, adjust tabs, and larger boats with 25 or 30" legs will better handle a wide variety of conditions). If you really need to dial it in for a wide variety of conditions, and can't get something you are happy with, then a hydraulic jack plate is likely the way to go.

A stepped pod, like OPs, is going to be the least predictable in advance (vs a hull extension pod) and you need to test it on the water and be willing to adjust it a few times.

 

[Sr SQ]

Yeah but that's a stepped pod, at least it's what it looks like. I've seen some have to go up as far as 2 inches per foot of setback

Agreed...
As mentioned jack plates may be the only way to get the hight you need without drilling new holes......and a cool toy LOL
Try raising them what you can (looks like just one hole left ) and see if there is any improvements.
In my experience dialling in the mounting hight of an outboard has had very worthwhile impacts on performance, and generally an overlooked step in repowers or other mods that change the weight distribution of a boat.
When I changed out the light 135s for the heavier 200s I had to raise up 1" on my searay, the boat only gained 1-2mph but was much more nimble and handled like the lighter motors.
I don't truly understand all the science behind it but in the 1/2doz boats I have experimented with, everyone benefited from lifting the motor, some allot.
With and average load and sea conditions lift till it porpoises or vents in turns with a reasonable amount of trim, fine tune with prop selection.
Jack plates add setback also that changes things, I borrowed one to dial in a boat once and when I removed it and put the motor back on the transom I had to lower the motor from where it was on the jack plate one hole, so its really a one on one relationship with each combination.

​

 

[Max123]

I'm curious about OP's mounting bolts. Most boats require x4 bolts, one in each group of holes. Looks like OP has x6 bolts? x4 in the top mounts, and x2 in the bottom?

Are x6 bolts required on the DF300 (I've never mounted something that big)? If OP is able to remove the 2nd set of bolts in the upper mount, then he can raise up x3 holes (2.25")

 

[ship happens]

Agreed...
As mentioned jack plates may be the only way to get the hight you need without drilling new holes......and a cool toy LOL
Try raising them what you can (looks like just one hole left ) and see if there is any improvements.
In my experience dialling in the mounting hight of an outboard has had very worthwhile impacts on performance, and generally an overlooked step in repowers or other mods that change the weight distribution of a boat.
When I changed out the light 135s for the heavier 200s I had to raise up 1" on my searay, the boat only gained 1-2mph but was much more nimble and handled like the lighter motors.
I don't truly understand all the science behind it but in the 1/2doz boats I have experimented with, everyone benefited from lifting the motor, some allot.
With and average load and sea conditions lift till it porpoises or vents in turns with a reasonable amount of trim, fine tune with prop selection.
Jack plates add setback also that changes things, I borrowed one to dial in a boat once and when I removed it and put the motor back on the transom I had to lower the motor from where it was on the jack plate one hole, so its really a one on one relationship with each combination.

​

Jack plates work awsome if dont mind a bit more weight back there.

The science is basically the water coming back up from the surface in which the hull itself made a carving in. Its the carving that is on its way back up to water level basically if that makes sense. The science continues on with the deadrise and shape of the hull a bit as well. The more of a carving it makes etc. The further back you stick the wheel in the water the more level to the water line the cavitation plate needs to be. The amount of drag just by being one inch too low, is quite interesting. You would think its not that big of a deal or that noticable but that could be the difference between a couple hundred RPM for example. Just depends on the individual boat. Its pretty cool

 

[Sharphooks]

Thanks for the comments, gents. Jack Plates, eventhough I recognize how you can really dial in outboard height and performance, ain't going to happen due to weight. I just burned off a huge pile of southern pesos converting to lithium. The main reason I pulled the trigger on the conversion was to get 250 lbs of lead acid house batteries out of the stern (4 x 6 volt Interstates) and replace them with an 80 lb Battleborn (and solar panels on the wheelhouse roof)

I just got back from the boat this afternoon because I wanted to try out that slick Victron tech where you download the Victron application on your phone in order to see voltage, amp hour draw and everything else that's going on in your system --pretty slick. I should have gotten a side view of the Suzuki legs but I was focused on other stuff. I'll do that next time I'm at the boat, but very helpful suggestions and comments...thanks again.