Peter White answers your powerboating questions
Author: Wiley Nautical
Author of Powerboating (3rd edition), Peter White answers your powerboating questions.
Peter White has over 35 years sailing experience and is a former police officer with Sussex Police. As well as being the creator of the RYA Personal Watercraft course, he is the principal of Seafever training and leads Honda’s Powerboating training.
Find out how you:
Approach a narrow entrance Solar Power Keeping your stern in line Miles per gallon Miles per gallon when choosing a boat
I often have to approach a narrow entrance to a pier leading to a slipway. If the wind is at 90 degrees to the pier I have to allow for that in my approach which will now be at an angle. This means I can't see until the last moment if a small boat is coming out from the slipway. When this happens and | have to go astern I continue to be pushed downwind. There is little room to manoeuvre because of shallow water and moored boats. What is the best way of dealing with this? Ken
Peter says 'Interaction between vessels is a very interesting subject. As the two vessel approach, the bow wave will cause a pressure wave, initially pushing outwards. As it reaches your boat your pressure wave also moves outwards and both pressures push the bows away. However, having now pushed past each other there becomes a low pressure area amidships. One is now drawn towards the middle of the vessel as the midway under-hull suction draws you in. Following on is the stern pressure wave, again initially pushing outwards until one reaches beyond its stern where water is sucked into the propeller area.
If you are dead in the water or moving slowly the other vessels forces have little to work against. You will be pushed around similar to a log in the water. One must be aware of hull sizes shape and weight including depth of water under the hull. A larger vessel will usually create greater forces. Remember this will all be taking place at displacement speed and it is not uncommon where boats are moving at this speed, or too quick in shallow water to vacuum their hull to the bottom of the river or canal and stop dead, technically run aground and once they have stopped the water moves back under the hull and they can move forward again.
The wave pressure will also bounce off the banks of the river or canal as reflective waves and come back towards you from the sides. Boats moving along a canal can use this pressure to avoid hitting the sides. It is possible the water level in the area of the boats will rise as they pass. Taking a cubic metre of waters weight as 1000 kilos [Tonne] a small lateral movement of water will have a considerable effect on the handling characteristics of your vessel.
If you have room to manoeuvre and the approaching vessel is of similar size maintain your speed and steering. I trust you are suitably protected with the use of fenders.'
I wish to use a solar panel to power my bilge pump when I am away from my Boston Whaler Montauk 170. Could you make some recomendations? The bilge pump is a fully automatic Rule 500 pmcnamee
Peter says 'The bilge pump shouldn’t be required to work very hard if the Boston is covered and protected from the rain and assuming hull integrity is sound the solar panel should only be required to keep the battery topped up. You would need to seek advice from a specialist in the Solar Panel field.'
When traveling down a marina aisle on a twin engined out drives motor boat with a strong wind blowing you sideways I usually use just one engine ahead to keep the bow heading toward the safe side (up-wind) of the aisle. However, in quite a strong wind the stern of the boat will drift downwind even though the bow is keeping upwind (meaning I'm moving sideways down the aisle). How do i keep the stern in line? T Moss
You are correct to keep the bow up to windward. You don’t say which engine you are using to maintain headway. If the wind is from the starboard side you would be keeping the bow up to starboard. Stern would be hanging off to port. Using starboard engine on tick over ahead, just touch astern on the port engine – this will pull the port stern up into wind and you will note the bow will swing to port which you don’t necessarily want to happen. One has now slowed the hull and twisted the hull position more parallel with the marina aisle. Only touch the port engine for a minimum length of time, slowly.
If your marina has a large aisle you may be able to experiment with the engines where you have manoeuvreability and room to escape. Remember the stern of the boat will always move up into the wind when going astern. If in difficulty place the boat with stern into the wind and relax!!
Important – if the conditions are such that you do not think that you have the required skill or the conditions are really bad. Back off and place the boat alongside a visitors berth that you know you can reach safely. Wait for the conditions to improve before moving the boat alongside your berth.
I have just perchased an Farline Carerra powered by a Volvo 260a petrol engine, Now this Boat I believe has a planning hull but mine wont go over 2000 revs under load but out of gear she will rev happily to 5000 I will taking her out to Sea soon but i'm very wary that I dont have the speed to get out of any trouble, Can you help. Leo
Suggest you have the boat checked over and refer to Volvo. You may find my answer to the Aquador 28 problem re the fuel consumption helpful. You don’t say age of vessel or hours worked. Ask your engineer to do a compression check on the engine?
I have an Aquador 28 with a volvo D6 310HP engine and outdrive. Before purchase I looked at the Motor Boat Magazines and they gave fuel figures of 4 mpg at 20+ knots for the boat with the same engine. I fail to get better than 2.2 mpg despite trying all of the trim combinations. Am I doing something wrong or were they cooking the books? solentss
They wouldn’t be cooking the books but in test conditions their figures on fuel consumption maybe in ideal conditions with calm seas and light wind. I don’t know. If you have an issue you must speak with the manufacturers.The following is just a suggestion. Fuel consumption can be down to many, many facets and I will list just a few. I am not meaning to sound rude but how long is a piece of string?
- Condition of the hull – clean or dirty.
- Quality and age of the fuel – clean and fresh – dirty and stale
- Throttle settings – 2500rpm may give the same speed through the water as 2800rpm. Loads of unnecessary fuel can be used.
- Travelling into the wind will use more fuel than travelling downwind
- Playing the throttles up and down can consume masses of extra fuel for no benefit on performance
- Loading – where are they seated and how many people onboard
- Full tanks of fuel and water
- Condition of the propellers and condition of the outdrive leg.
- Using trim tabs in such a way that they work against the trim of the leg.
- How old is the unit and when was it serviced last?
Thank you for all your questions
