More fun in the aerotec

[simonafloat]

Hi all

Been messing around in our aerotec 420 most weekends recently, it's a lot of fun! Finally got a decent pump with gauge so everything is now inflated correctly and she absolutely flies along. The mariner 15 got 3 large adults and a child up on the plane yesterday, to be honest I think that's its maximum, any more weight and she'd struggle.

The taw torridge estuary is ideal sibbing territory and they don't seem to be bothering to collect slipway money anymore the ocean swell was right into the estuary yesterday so we spent hours driving into the waves, the boat will handle anything the only limit is how much your own body will take! We were out for 5 hours which is pretty much the entire tide window and looking at the tank I'd say we used about £15 - 20. Not bad seeing as we were at WOT most of the time.

[jeffstevens763@g]

Sounds like a good set up there Simon and a smile ear to ear for the 5 hours.

[simonafloat]

Here's our 420, beached at Instow last weekend. The wheels work well, got them off eBay.



The only downside with the 420 is that if I ever replace it I'll have to sell the engine too (it takes a long shaft outboard) not quite sure what their logic was with this, I can't see why they couldn't have made both as short shaft setups.

[Fenlander]

I've puzzled about the long shaft motor fittment on the 420 in the past. I wonder... do you still get that excessive splashing over the transom like the 380s suffer?

Also it was commented here the other day if the 420 has taken the length just a bit too far to keep the air floor stiff... do you get any flex issues?

[simonafloat]

Originally Posted by Fenlander

I've puzzled about the long shaft motor fittment on the 420 in the past. I wonder... do you still get that excessive splashing over the transom like the 380s suffer?

Also it was commented here the other day if the 420 has taken the length just a bit too far to keep the air floor stiff... do you get any flex issues?

... I did get some splashing but solved it by raising 30mm. Wash is nice and clean now. I haven't tried a 380 so have nothing to compare to. The airfloor flexes a little towards the stern but only a fraction. Do 380 floors feel rock solid? I can see why they stopped making the 420, 400mm difference in size really isn't enough to warrant manufacturing and stocking 2 models.

I had to do two patches on the airfloor under the flat decking layer. In order to do this I had to cut a fair bit of the flat layer off. I wonder if this has affected the overall stiffness of the floor..

[Fenlander]

If a 30mm spacer gives a clean wash that's a better result than the 380's shorter transom which... in my experience... is only slightly improved by a spacer but still a very splashy wash.

Yep the 380 floor is totally rock solid. I don't think removing the joining flap to some degree would affect it. The "structure" strength of the V is really between the floor edges where they sit at the tube/floor interface and the join at the bottom. I think once inflated you could take the whole flap away and it would be fine. It's my impression it's really only there to give a little bit of flat floor to slightly normalise the V shape.

It would be very easy to glue in a new section if you wanted to for any reason.

[simonafloat]

Spent yet another weekend messing about on the estuary. Before the rest of the family turned up I had an opportunity to take the boat for a spin with just me on board. Not sure what speed I was doing as I forgot to take my gps but it felt plenty fast... But the prop wash was really splashy even with the packer under the outboard. With one extra person or more onboard the wash is clean as a whistle. I guess less weight = more freeboard = splashier wash. Does that tally with other people's experiences?

Big tide next week, tempted to pull a Sickie and see how far up the torridge I can get...

[Bombardc2]

Hi Simon, we saw you out there on Sunday. We were in the blue ribcraft. The Aerotec looked really good out there!


Sent from my iPhone using RIB Net

[simonafloat]

Originally Posted by Bombardc2

Hi Simon, we saw you out there on Sunday. We were in the blue ribcraft. The Aerotec looked really good out there!


Sent from my iPhone using RIB Net

Cheers, thanks for that! Was a great days boating. Was that the ribcraft with the tohatsu on the back? Do you launch there often? Hope to see you around again.

[Bombardc2]

That's the one! I used the launch there all the time when we had inflatables but haven't been for a while. I do plan to launch there more often again. I'll say hello next time I see you! We were beside you at one point and think you were touching nearly 20 knots 🚤! If you want to venture a bit further at some point but want a bit of back up drop me a pm.


Sent from my iPhone using RIB Net

[simonafloat]

Originally Posted by Bombardc2

That's the one! I used the launch there all the time when we had inflatables but haven't been for a while. I do plan to launch there more often again. I'll say hello next time I see you! We were beside you at one point and think you were touching nearly 20 knots 🚤! If you want to venture a bit further at some point but want a bit of back up drop me a pm.


Sent from my iPhone using RIB Net

20knots sounds fine to me! I'll PM you as we were toying with a trip over the bar and beyond.

Simon

[Fenlander]

>>>think you were touching nearly 20 knots

Is that with a Mariner 15? If so you are getting every bit of performance out of that setup... and no loss of speed for the 420 over the 380. Excellent.

[simonafloat]

Originally Posted by Fenlander

>>>think you were touching nearly 20 knots

Is that with a Mariner 15? If so you are getting every bit of performance out of that setup... and no loss of speed for the 420 over the 380. Excellent.

Yes, using a 2006 mariner 15 longshaft. With freshly changed gearbox oil

Simon

[Max...]

If that is GPS verified I'm very jealous.

Anyone comment on why mine is slower?!

http://www.rib.net/forum/f50/bombard...tml#post694656

[Fenlander]

I can't think you have anything wrong Max but the advice we'd both give a newbie...

Aerotec:

Inflated to pressure and rechecked in the water?

No weed growth - ha ha.

Load not excessive?


Mercury:

Reaching WOT?

Compression check?

Carb clean?

Prop perfect?

Prop pitch?

Transom height/trim angle setup?

[Nick Hearne]

If my memory is right 18 knot is about right for a 15hp on a 380 Aerotec.

[Max...]

That's what I thought Nick but this has always been Fibnet hence I'd like to see gps verified speeds only! It all depends on load too of course so people need to post their load weights. To summarise in say F3 chop I get around 16.5 to 17 tops, maybe it might say max (for a second 17.2). Load around 160kgs.

Check all that David bar as noted that my Tiny Tach broke so need to get another to check revs at WOT. Don't have a compression tester though...

[Max...]

Hmmm, just found a post from a while back (!)

http://www.rib.net/forum/f50/380-15h...tml#post632018

Originally Posted by Max...

Nasher - finally got round to doing some runs with the tacho on today.

Mariner 15 with standard factory prop.

Best trim position was 2 and achieved 5750 rpm max at WOT. Touched 19 kts lightly loaded with myself 12 stone and young son around 5 stone.

I've lost a bit off the top!

Another topic on this here:

http://www.rib.net/forum/f50/y-class...p-44812-3.html

[simonafloat]

Originally Posted by Max...

That's what I thought Nick but this has always been Fibnet hence I'd like to see gps verified speeds only! It all depends on load too of course so people need to post their load weights. To summarise in say F3 chop I get around 16.5 to 17 tops, maybe it might say max (for a second 17.2). Load around 160kgs.

Check all that David bar as noted that my Tiny Tach broke so need to get another to check revs at WOT. Don't have a compression tester though...

I had planned on taking a GPS with me but left it in the car... Next time I'm out I'll do a proper speed check. But for now, I'm claiming 20

[chris123]

Just remember to always do a speed check over two legs on reciprocal bearings - tide / wind / waves can easily shift your top speed by +/- 2 knots or more.

Cheers

Chris