A speed test for my Gen IV Bote.

Some time ago I decided to do some testing with different size outboards on my 10' Portabote.
I posted the results in the forum.
I was having problems with my old 4hp outboard and was looking at buying a new one.
Here is a copy of my post:

"Well guys,I finally found out the cause of my thumping transom.
Went out on the river today with Jamie (The forum member with an engineering background, Thanks Jamie)
We tried a couple of his outboards and I was very pleased with the result.

Let me first state that with my 4hp 2 stroke engine I am able to attain 20kmh (12mph) but it has an intermittent thump.
I weigh around 100kg and I also had a small 12 volt car battery on board but that's about it other than 5 litres of fuel.

First of all we tried Jamie's 5hp 4 stroke (2 years old) and the maximum speed I was able to attain was between 17 and 18 kph (10.2 mph and 10.8 mph) a little slower than my 4hp 2 stroke.

Next we tried Jamie's 7.5 hp 2 stroke and I'm sorry to say I couldn't get it to plane.

I couldn't get it back down onto the water to plane - It was flying! (Just joking about not planing).

It planed very well and I didn't have to move from the rear seat to the middle seat to do so.
I was able to go 26kph with the 7.5hp 2 stroke even though it's a 1980 something Johnson. That's 15.6mph with a standard transom.

(Thanks again Jamie.)"

I have settled for a 5.8 hp Parsun Outboard which, technically is a little over powered for my 10' Gen IV bote.
The maximum power rating according to my compliance plate is 5hp.

According to Portabote the maximum recommended safe hull speed is still 15 mph even for the new Alpha series.
It also appears that the maximum hull speed is, as indicated by Portabote, 15mph (24 kph or 13 knots).

Cheers,
Matt

Quickboat and Portabote maximum speed and benefits of each.

Portabote.

Portabote has been on the scene for quite a few years now.
There have been competitors in the past but most seem to have disappeared over the years.
Here in Australia we had our own version named the "Flatout Boat".
It was very similar to the Portabote but for some reason it didn't seem to take off very well.

The main positives can be summed up in the words of Sandy Kaye, CEO of Portabote:

"The Portabote was never meant to be a speed boat but rather a safe vessel for both boating and fishing."

In regards to safety, the patented "Flexy Hull" has proven to be very effective in handling chop in rough water, something that I have experienced myself.
The Portabote has a level floatation rating which means that should the vessel be swamped and fill with water it will remain level and still float.
This floatation is achieved by the use of floatation foam fixed to the hull just above the seats.
The seats too contain floatation which adds to its safety factor.
The plastic hull itself has a certain level of boyancy.

Due to the flexible hull the maximum recommended safe speed for the Portabote has been limited to 15 mph (24 kph or 13 knots).

Should you decide on using a 9.8hp outboard for your 14' bote, it is also recommended  by Portabote that the throttle be kept to a little over half full throttle as any more will have little effect due to maximum hull speed and it will result in excess fuel being used for no reason.
It is also recommended that you avoid sharp turns at speed in a Portabote.

Quickboats

After passing hands a couple of times, the Flatout boat was eventually bought by Quickboats who totally redesigned their folding boat.
Deryck Graham, one of the partners of Quickboats and brother of James, is an aeronautical engineer with quite a lot of experience with composit materials, which is what the Quickboat is made of.
The hull and transom of the Quickboat are both rigid, and result in a vessel that is safe, fast and responsive.
It too has level floatation capabilities but the flotation is acheived through the composit hull material from which it is made.

In regard to maximum speed of the Quickboat Deryck Graham had this to say:

"Two people on board at say 70kg each with 9.8hp sees the Quickboat capable of 22 knots.  At this speed it hits the limit of the prop pitch."

In response to another review that stated:

"........ the faster it (the Quickboat ) goes, the more rigid the hull becomes."

Deryck continued:

"The Quickboat is high tech but i have to admit it does not morph into a more rigid boat than it already is at speed. :-)"

Kind Regards

Deryck Graham
Managing Director
Quickboats

For those that are curious, 22 knots equates to around 25 mph or 40 kph.

Quickoat maximum speed and reviews.

Here is an interesting review on the Quickboat that I came across.

Quite good information but there are a couple of things that I don't agree with in this review.
The first is probably subjective as beauty is in the eye of the beholder.
In that review they state that the Quickboat is "Perhaps not the prettiest 'dory' around town."

I actually like the design of the Quickboat and in my opinion it is a modern, smart looking craft.

The second thing that I don't agree with can be seen under the "Engineering" section of the review.

Under that section they state that, due to its design, the faster you go, the more rigid the hull becomes.

That may have been a personal observation on their part, but to be sure I did as I do and went to the manufacturer of the Quickboat for confirmation.

I sent an email to Deryck Graham and this was his reply:

Hello Matt

Two people on board at say 70kg each with 9.8hp sees the Quickboat capable of 22 knots.  At this speed it hits the limit of the prop pitch.

The Quickboat is high tech but I have to admit it does not morph into a more rigid boat than it already is at speed. :-)

Kind Regards

Deryck Graham
Managing Director
Quickboats

www.quickboats.com

That is what I like about Quickboats.
They are upfront and their dealings have always been honest with me.
There is no feeling of being competitive with the opposition and never an unkind word against them.
Their mantra has always been that there is room enough for all in the world of folding boats.

Quite impressive speed I think for a foldng boat.

22knots equates to 40kph or 25mph.
Absolutely brilliant!

Tight lines and screamimg reels,

Matt

Stainless steel rods?

Well, I did it again.
Once again I asked the CEO of Portabote about the flexing transom.

I sent an email off to Sandy Kaye, asking him if he could tell me why they allow a flexing transom.
I also sent a number of possibilities as to why this could be the case.
These possibilities are:

1. Safety. Because you have to angle the outboard, optimum performance cannot be achieved as stated by a few forum members and this will limit maximum speed. (I have experienced this myself in that my 10’ bote goes a lot better if the outboard is vertical, it just hits the back of the bote.)

2. It has become necessary to have a thinner transom to accommodate the folding transom.

3. It’s just a side effect of having a plastic transom and now a thin metal one.

4. Cost. You are trying to keep the cost down as much as possible for your customers.

5. Weight of the bote to be kept to a minimum.

I was pleased to receive a reply almost immediately and this is what he said:


“Thank you Matt,
You stated a lot of the correct answers yourself.
I wish you had a chance to actually use the Bote with the folding transom. It flexes when you start. But then the vertical stainless steel rods help to rigidify it pretty well.
We have quite a few out there now and people seem to be satisfied with the performance.
The picture that I sent you does show how well it performs.
Thank you again for asking these good questions.

Sandy”



Having read his reply, I have a couple of concerns.
I don't how effective the stainless steel rods (which are used to keep the transom folded. There are two of them) would be as they are about the size of small tent pegs.
In any case, they couldn't be very strong, strong enough to prevent flex anyway or to have much effect..
Sandy's reply also suggests that there are other reasons that are not mentioned.

The question was also raised again in the forum in regard to maximum safe  speed for the new Alpha series bote.

In response Sandy re-iterated that the maximum safe speed for the Alpha series would be about 15mph (about 13 knots or 24 kph), after which the hull begins to spread at the sides and becomes a little unstable.

This spreading hull has become known as "flexisplay", a term coined by Paul from "The floating log" blog.

Sandy has also recommended that when using a 9.8hp on the 14' Alpha series you should limit speed to a little over half throttle and went on to say that any more than that would be of no value due to maximum hull speed and it is a waste of fuel.