Seamax Return.-

[Sea Rider]

After horrible water performance and ungluing seam issues with previous Sea Max 420 alum Sib inflatable, dealer decided to be a good Samaritan due to being legally close to suit him for selling crapy boats. Took 3.5 months to ship a brand new 430 alum Sib which replaces previous 420 model. Although the waiting has been a long one, was very fruitful. This new point bow model assembled in China for the Canadian Market is a heavy duty one, has reinforcements under lower tubes and some extra gadgets on upper tubes. It's a close copy of a JB inflatable with other brand logo.

Spraying soapy water inside deck and on side alum floorboards for a quick floor set up is the way to go, after finishing initial installation all chambers were inflated gradually with an electric pump to 3.0 PSI. Being a large sib with fat diam tubes would have taken an eternity to inflate to its working pressure with simple delivered foot pump.

With a 2 stroke short shaft Tohatsu planes very fast, as engine is still undergoing break in process first outing was limited to just 3. Fully inflated achieves good overall water performance on flat calm and slight choppy waters. Had completely forgotten the feeling about riding a noisy alum floorboard Sib compared to a hard hull Rib.

One important issue, there's always one, the Sib was delivered with 40 Cm transom height when it should have been delivered with 35. The problem is that engine sits way high on transom, although it produces a near flat middle wake, has prop aeration issues on choppy sea cond and at tight close turns at speed. You can't possibly send 40 Cm transom height along huge 50 diam tubes that compensates installing less height transom which produces better performance under all water cond. To be clear a 35 Cm transom height will dial sweet engine /transom height. It it were mine would chop middle transom 5 Cm off, assume owner will not share my crazy maximization insights....


Happy Boating

 

[alanfox55]

So this is a friend of yours who owns this boat?

 

[Sea Rider]

He's a friend who embarked with this brand on his own and a customer at same time as I sold him the engine when he already had bought a brand new 4 stroke Merc 30 HP with out of this world 70 Kg in weight. A spine breaker if sitting and removing engine everytime combo will be used which is often. Tohatsu 2 strokes only weights 52 Kg. Anyway no matter which engine brand he sits on a 40 Cm transom will have same aeration issues as described above.

It's not a matter of adding more passengers or weight, even trimming engine up to lower engine while Sib is on plane as there's 2 inch gap between upper water deflector plate and lower anticav plate along exposed anticav plate included. To understand pic, water flow at speed swirls up through front sharp angle of attack and bangs right under water deflector plate to be redirected sideways as opposed to achieve water flow passing flat under deflector plate which is the sweet engine/transom height for Tohatsu and any other brand engine. A matter of sitting them at proper height to achieve this condition.





At least on these newly released 430 sibs Seamax has lost completely its course. With less transom height It's a much simply job to shim up an engine as opposed to chopping middle transom down to sit engine at the sweet transom height.

Happy Boating

 

[alanfox55]

Thanks for the info.

 

[Sea Rider]

Some updates :

Have installed a Hardline hour/tach meter on engine's middle tiller handle, owner is most pleased, was driving hin nuts to manualy write down the boating hours on a log booklet. Hardline meter toggles between hour and rpm readings by pressing a small platic actuator. With engine off while in rpm mode can read max achieved rpm, that's a plus compared to my TT.






In 2 outings owner has learned how to balance deck weight and passengers properly. Sib's tubes are previously infalted to 3.0 PSI and keel to 5.0 PSI right before launch, being assembled with thick PVC doesn't need a re inflation once on water, wide tubes feels very solid.

Owner is still bit affraid to hammer down the throttle, personally wanted to check combo's full wot rpm, but impossible ridding side of him on my Rib. When told to make a wot run he only throttled to 4850 revs and that's not the max wot rpm that a 30 HP will go powering a light Sib with just 2 up. Seems will need to personally wot trial that combo as if stealing it to check that out including GPS top speed. That's what tach & GPS are for..



Owner already knows about the engine/transom height difference and the prop aeration experienced on close turns and at choppy sea cond, will need to live with it unless gives me green light for a transom chop down optimization. Yesterday outing was the best have seen in weeks, water was flat dead calm, no wind whatsoever, could light a match. Sailboats were left stranded at sea. If it's El Ni?o mischiefs, you have my vote ni?o. LOL!!

Happy Boating

 

[alanfox55]

I fully agree on that!

 

[Sea Rider]

Today the sea was flat calm, went for a wot spin with lightly loaded sib and 2 up, guess what only 4850 rpm achieved at full throttle. 2 issues calls my attention :

-Factory deliverd prop is 9 x 13, with reason revs are 1 K low, wot range is 5200-5850, will need to buy a same diam prop with 11 pitch, 2 less pitch difference will put the engine right at 5850 as previously loaded and 2 up. As that combo will be used mainly with max 3 boaters not an issue loosing some top wot rpm.

-AV plate is highly exposed loosing around 150-200 revs at wot, in order to gain that lost rpm will need to chop down transom 2" , if we add 200 + revs to the expected max 5850 revs with 11 pitch, engine will benefit transporting a third boater and staying in the 5850 rpm range.

Happy Boating

 

[Sea Rider]

Whie waiting for a Tohatsu 11 prop pitch to arrive to put the OB in the sweet max 5850 wot revs, performed a visual check up of the carb/timing advance synchro, to my surprise although carb has a full opened butterfly at full grip, the timing advance synch was under advanced by 3.5 deg.

This OB is so simple and friendly to play with that in 30 seconds was set at 25?. Now is producing 4950 rpm, still near 1 K less that max. Nevertheless OB has a much faster hole shot and works fantastic well thoughout the whole throttle range than before.



The new 11 prop pitch should fly that light 430 Sib to Mars...

Happy Boating

 

[Igyjastabay]

What is the length of the sib, 19" tubes? Nice looking boat

 

[Sea Rider]

It's a 14 footer Sib, tubes are 20" or bit more, color combination is very eye catching.

Happy Boating

 

[Sea Rider]

In December wonderful things happens, owner has fully agreed on a transom chop down along a prop maximization. Called the cutter man, he's always willing to chop transoms down as directed.

First step was to remove both outer and inner engine plates, mark middle transom center..



Mark the width of the swivel bracket on top transom...



No time for repent....



Chopping middle transom down..



Shaping cut sides for upper motor to fully turn sideways...



Coarse finish, final finish is pending. Tomorow will test combo on flat calm, no wind water cond and visually check water flow passing at speed through lower leg. The distance between upper small water deflector plate and Anticav Plate is 8.5 cm, the middle chop is a conservative 7.5 cm cut. If all goes well, flow should pass very close under upper water deflector plate. Fingers crossed..



With higher water level and top prop thrust, should see some slight rpm reduction as the blade will grip, move more water much better than before, nothing that a prop maximization can't handle..

Happy Boating

 

[Sea Rider]

Made the water test as indicated previously, now that prop sits much deeper, hole shot is outstanding, OB middle wake exit is flat, close dime turns are superb, handles more weight more efficiently than before.



As there ain't no formula on how much transom needs to be chopped down, it's a matter of pure wild guessing. Prefer one single cut no matter if OB sits too high as opposed to cut transom again. Being transom 4 cm wide it's impossible to make one single clean cut through the entire transom width as the cut needs to be done at both sides and hope there's a perfect both sided clean cut match.

Water test showed that OB sits slight down, water flow at speed is passing slight above upper water deflector plate (3) through the non edged area causing small water splashes sideways. Sweet OB/transom height for that horse is right under (2). As before (1) the combo performance improvement is awesome. Will add wooden shims to sit OB bit higher and test till has 0 water side splashing, once correct height is dialed, will have transom finished as when factory delivered along a prop maximization.



Boating to far away distances has turned highly productive, had a wonderful & plenty parmesan scallop lunch. Bon Appetite!!



Happy Boating

 

[Sea Rider]

When thought that playing with shims will dial the definitely sweet lower leg/transom height paramount was wrong, although water flow is now skimming right under upper water deflector plate when on plane, at speed on slight choppy water cond there's a slight prop aeration.



As water flow at speed is not exiting completely flat under middle lower transom, decided to disassemble the alum floor as to have a clue on what's going on, found the following flaws :

-The shade tree factory technician has glued both front and rear inflatable keel ends vertically instead than flat horizontal to alum floor. When keel is fully inflated to its working pressure, the rear end presses hard into middle transom lower fabric and forms a small bulb.



This 430 has a shallow V lower transom which does not assures flat even water flow passing under lower middle transom. If sitting OB slight downward, water flow passes over upper deflector plate, aeration is canceled, but there's slight water splashing back transom as flow is not being cut through the lower edge located right under upper water deflector plate.

Factory Flaws :

-Huge front keel bulb floats front Sib too high, ideal is to have a smaller keel bulb up front for Sib to ride with more tube's length on water riding parallel to water level.


-Too much rubber reinforcement has been glued side of tubes right under where lower deck fabric begins. The fabric tent shape formed under deck when keel is inflated is not even stretched. Rubber under reinforcements are badly glued as in pic. Very poor quality control or total lack of it.



-Although the Sib is eye catching, tubes are too big in diameter, floor is very wide, has poor 4 piece side joiners configuration, alum floor bounces excessively at speed.

For testing tubes, keel were inflated to maximum recommended pressure with gauge. Got really tired testing different shim heights, playing with trim and deck weight with no avail whatsoever.

As can't have both neat working parameters at same time, unless Sib undergoes a extensive factory flaw removal, owner knows about these new flaws found, must decide if boating having slight aeration on choppy water cond, or no aeration whatsoever, but with water splashes back transom..



Bottom Line : Sea Max 430 is only good as a rescue Sib at just fast displacement speeds, or as a fishing platform, Not Recommended as a speed inflatable for top water performance & fun..

Happy Boating

 

[Sea Rider]

This pic illustrates the higher bow riding attitude when on plane at speed, doesn't get any better if more weight is added around bow deck. It's a keel bulb flaw issue.



The pic was shot while water flow was passing skimming right over upper water deflector plate, back splash is visible, much worse at full throttle. The only redeemable is that there's 0 prop aeration. The new bummer is : if going for a prop maximization to pull needed 1,100 wot revs up to its max 5800 wot range. Will achieve more water splashing backwards and in the other hand with water flow skimming right under upper deflector plate worse aeration...

Happy Boating

 

[Texasmark]

Really nice presentation sir. I'm impressed.
Mark
------------------------------------
On a side note a Turning Point Hustler hundred bucks alum should be cupped like the 13+ diam. used on my 90 which should reduce or eliminate the ventilation problem you mentioned. I don't know if it's ported or not but you don't need the ports anyway with the hole shot you mentioned.

Did you get back with he Sib mfgr. and point out his mistakes? If so, what did he say? What did the owner say?

 

[Sea Rider]

Thanks Mark,

The prop is a OEM Tohatsu 13 pitch prop delivered with the 30HP OB, it's highly cupped. Have used same OB's in different set.ups with 0 aeration or back water splashes whatsoever when OB sits at the sweet transom height. Wrongly assumed that by chopping transom down will resolve forever the excessive aeration the Sib had due to OB sitting way high as seen on post 3.

Have shimmed transom up 1/2 cm, should lessen water splashes sideways, needs a water run to confirm that. Useless blaming dealer or manufacturer for, they will wash their hands as Pilathus did, will ignore the tech flaws or even blame me for having chopped transom down.

Was a bad inflatable brand purchase right from the beginning as this is the second Sib the delaer traded in as the first one simply became near all unglued in a very short time period. The first one had a much less diam keel bulb and run more horizontal once on plane.

Happy Boating

 

[Sea Rider]

As don't like doing partial combo optimizations, worse if compromising neat water performance, removed complete inflatable keel and corrected factory flaw found on both keel ends. Now both rests completely flat under alum floor. On last water trail we were about to dial the sweet OB transom height needed, testing shimming transom up by +,- 1 cm shims had no avail. Taking into account that upper water deflector plate is only 3 mm thick raised another 5 mm using a hardened cork shim glued onto transom's cut.

Solo boating test at open sea with slight choppy water cond proved superb. The keel redone and the 5 mm shim dialed the desired sweet transom/lower leg height match. When applying just 1/2 throttle combo jumps immediately onto plane, that's once water flow engages and skims right under lower upper deflector plate, no need to weight balance Sib up front whatsoever which is a 1+. Neutral trim as in pic was dialed 3 holes out transom.



On flat calm water cond, sib rides near parallel to water level with 0 prop aeration or water being deflected sideways of lower leg. Just a slight side water deflection on choppy water cond at speed which doesn't slow down the combo. it's the nature of the beast having a small V lower transom end. Last work to be done is raising transom back up with one piece 3.5 cm wooden shim bolted onto transom, fiberglass it nicely and reattach both front/rear OB plates as factory delivered.

Before the last water test, OB was revving at 4700 wot rpm with 2 up, now at 5300 wot rpm, has gained + 500 wot rpm. Will test again once transom has been finished, if dials same, will only need to re pitch OB with a OEM 12 pitch prop from current 13, should dial max 5800 wot rpm factory stated, fingers crossed...


Happy Boating

 

[Texasmark]

So the original problem was the hook in the hull, not the transom height?

 

[Sea Rider]

So the original problem was the hook in the hull, not the transom height?

Was a combination of the hook, lower transom small V and OB height. A Pandora Box conveniently boxed.

Happy Boating

 

[Sea Rider]

As the original cut was made at sight, needed to be angled to 90? for OB to sit straight on middle shim.



Fiberglass techie made a nice wooden shim half of what was originally cut, transom's cut was resin coated before shim was hammered down, both shim sides slit tight at both sides. Once resting on middle cut, shim was resin coated at 3 sides, once dried, sanded to match transom's width.



(3) 2 1/2 inch brass screws were screwed tight flat onto upper shim.



Last job is to repaint transom at both sides and rearrange both OB's front, rear plate to be even with middle transom border and enjoy fantastic boating. LOL



Happy Boating