What speed to expect from my tender.

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mikehibb

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Just curious really, only need it to pootle about.
Tender is Plastimo 2.6m flat bottom with wooden floor (not slats) O/B is new 3.5 Tohatsu 2st short shaft.
(yes I know that I will need to run it in for a few hours first before opening it up) Well it will if it gets delivered in time, should be arriving next week.

Thanks in Advance.
 
We have slats in a similar sized dinghy. We have a 2.5hp motor, previously 2.2.

Alone in the dinghy I reckon 4 knots, but it is rare that I would use it as such. Loaded much less, the most important thing is to stay dry and I tend to throttle right back and just cruise in and maybe 2 knots or so, once it starts splashing over the bow it stops being fun, especially if you are in good gear or have shopping on board.

I don't think speed is an issue until you get to little ribs where you are sat at a console and get up on the plane, before that the wet / not wet rule comes into play. Just my thoughts.
 
Our tender, tied to the yacht stern seems to do approximately the same speed as we do. I've never figured out how it knows how to regulate that, but when we are gunnels under, creaming along, it always keeps up, and when almost becalmed, it still never overtakes us, just stays about the same distance behind. Amazing!
 
I have the same outfit except the dinghy is a Quicksilver. One-up, on smooth water, it will plane and then go b****y fast, if you sit right forward. Two-up, though, no planing.
 
I have the same engine on my 8ft (light) GRP cathedral hull tender to get to and from the mooring. It does exactly 5 knots but doesn't quite get onto the plane. Haven't measured it with the inflatable but imagine it could plane 1 up and go quite a lot faster.
 
From theory the max speed will initially depend entirely on the weight in the tender. I think even one adult will stop it from true planing. However if it was skippered by a light weight child then the tender could plane in which case the top speed will probably be limited by the propeller pitch and max revs of the motor. One would assume this size of motor would have the prop pitched for low speed max thrust. olewill
 
I have a 2.65 with blow up keel and 4hp engine, It had max speed of about 5kn and would not plane even one up untill I fitted a spaller prop 6.5x6 instead of standard 8x8.5. Dingy is transformed, now planes at 12kn 1up and about 8kn 2 up still planing.
 
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From theory the max speed will initially depend entirely on the weight in the tender. I think even one adult will stop it from true planing. .....

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I'm 13 stone and I can assure you that mine planes, one-up.
 
Many thanks all, 4 knots will be fine for what I need.

However I am only 12 stone so might see if I can get it on the plane. The nephews will be over later in the week so no doubt they will get some fun out of it.
 
I can get my 230 inflatable floor to Plane in flat water with approx 16 stone in it, me and two 5 year olds at the front with the Mariner equivalent of the Tohatsu 3.5. Great fun but pretty wet and the prop cavitates when you get to max speed.
 
Well an update.

The Tohatsu 3.5 did not turn up in time, despite being ordered 6 weeks in advance. Apparently it got delayed in transit. Never mind though, after a few frantic phone calls by the supplier they offered me a new Mercury 3.3 that could be delivered over night, so I took that option.
Nice little motor, got a good 4-5knots out of it, more than enough for what I wanted. More details of the holiday later. Just got home and the sun is just coming up, need to get a couple of hours kip before work tomorrow (well might be a late start)
 
Some more feedback, and a possible slight change of plans.(As always with everything boaty)

No, not changing the O/B. But might change the tender.

The Plastimo 2.6 is good enough for my needs, but after a conversation with my sister, her kids are really looking forward to more sailing, but also want to to pop over to the little islands and bays near by and do some fishing/crabbing.

The 3.3 on the flat bottomed plastimo made a good 4-5 knots, but this was at just over half throttle, before we reached the hump.

So the next question is would an inflatable keel type tender get a bit better handling and speed and allow me to open the engine up a bit more?

The plasimo was a used one that came with the boat, and holds pressure in the tubes perfectly, so I can easily sell this on to offset the cost of an inflatable keel type tender.

Small rib is not an option, must be inflatable tender.

As always, many thanks in advance for suggestions.

Mike
 
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